Add 1.13 and drop 1.11 in order to get with the times.

Updates https://dmitri.shuralyov.com/website/gido/...$issues/3.

Changes that have an import path that doesn't correspond to any
existing directory, but do have a non-empty root, are considered
to belong to the root directory. Add them, so they show up as
expected when doing an import path pattern query that matches
a repository root.

This edge-case was originally unintentionally overlooked.

Fixes https://dmitri.shuralyov.com/website/gido/...$issues/5.

This code has gotten quite terse and hard to understand.
Refactor it, without changing behavior, so it is easier
to read and extend.

There are now two separated sections. One adds issues/changes to
issuesAndChanges. Another populates {open,closed}{Issues,Changes}.

The next commit will fix an omission.

Updates https://dmitri.shuralyov.com/website/gido/...$issues/5.

Previously, when using an import path pattern to query issues or CLs,
issues or CLs that had more than one import paths associated with
them had a chance of being displayed multiple times (if more than
import path matched the import path pattern).

Fix this by pre-computing lists of all issues and CLs along with
their import path associations, then use those lists when handling
import path pattern queries. This approach makes it easier to avoid
duplicate issues/CLs.

Fixes https://dmitri.shuralyov.com/website/gido/...$issues/4.

Also disallow multiple state query parameters.

This makes query parameter handling more precise and logical.

Use the same simpler style as in other projects.

Fetch to memory the latest commit of "master", "release-branch.go1.12",
"release-branch.go1.11" branches of all relevant Go repositories, and
then walk their trees to collect the list of directories. This scales
better than manually maintaining a list of Go packages.

For now, this is only done once at process start, and the release
branch names are hardcoded. This can be improved later.

Also add dl, example, mod, website, and xerrors sub-repositories.

Updates https://dmitri.shuralyov.com/website/gido/...$issues/3.

This functionality is factored out into a separate package
so that it can be reused across a wider set of projects.

I wasn't aware this method existed, that's why I wrote code
that does the same thing. Start using the Subject method now.

This change adds support for displaying issues/changes not just for
a single package at a time, but an arbitrary amount of packages that
match the specified import path pattern.

Reserved names "all", "std", and "cmd" are supported, and expand as
expected.

This makes the page rendering code in serveIssues and serveChanges
methods more consistently high-level, and as a result, more readable.

It will make it easier to add new similar issues/changes pages that
display entries for import path patterns.

This change makes minor frontend tweaks to improve accessibility.

Also use margin-left instead of padding-left, to avoid making the
"Packages" link area become larger on the left side. Using margin-left
instead keeps the space on left unchanged, without expanding the link.

Regenerate with:

	go generate ./...

Also regenerate assets to fix a gofmt formatting incompatibility
with Go 1.11.

This simplifies code, as fewer conversions are required.

Follows https://github.com/shurcooL/octicon/commit/c42b0e3b24d96976ecac81ef691662777b39ef64.

It should be beneficial to reduce bandwidth and speed up page load time.
Many dynamic pages will compress well (e.g., from 521 KB to 27.2 KB).
This is in large part because inline SVG are often repeated many times.

Only do so if the handler hasn't already taken care of compression.
This is determined by whether the Content-Encoding header is set
by the time WriteHeader is called.

This is a more consistent naming scheme. The detail comes first, the
interface name comes last. Similar to limitedWriter, nopCloser, etc.

Follows https://golang.org/issue/24836.

These checks are now performed upstream in maintner,
so no need to do it here.

Follows https://golang.org/cl/107296.
Updates https://golang.org/issue/21984, https://golang.org/issue/22060, https://golang.org/issue/24875.

It happened once in the last 24 hours, but I haven't been able to
reproduce it since. Log it with details in case it happens again.

Updates https://golang.org/issue/21984.

It's sometimes desirable to see all CLs/PRs for a specific Go package.
This change makes that possible via the https://gochanges.org domain.

This makes it easier to tell pages apart when multiple tabs are open,
or when viewing browsing history.

Use a little html/template to make this change easier.

Fixes issue 2.

These are minor changes, but they make the generated HTML look more
pretty and balanced.

Previously, only "golang.org/x" -> "x" direction was done. Now it goes
both ways.

For consistency and simplicity.

Previously, the import path was used directly as an issue title prefix.
This works for most import paths, but not for golang.org/x/... ones.
We need to map those to x/... prefixes.

Also simplify code in ParsePrefixedTitle.

Sometimes it's helpful to be able to see a list of all packages (and
their number of open issues) at a glance.

Since they're all on one page, it's easy to use the browser's search
functionality to find a specific package or parent folder.

If Accept header is set to exactly "application/json", respond in JSON
format.

The code to render a table of packages will be called more often in the
following commit. This refactor will make the upcoming diff smaller.

Rename isStandard parameter to give it a more readable name.

Some Go packages are not available for all OSes.

Doing a normal "go list" only lists packages that match the current
GOOS/GOARCH pair (darwin/amd64 in my case). So we run it with different
GOOS values to include all packages.

Add and propagate an application lifetime context. It's cancelled on
SIGINT.

Make logging more simple and minimal.

Regenerate with all golang.org/x/... packages in GOPATH, based on list
at https://github.com/golang/tools/blob/96caea41033df6f8c3974c845ab094f8ec3bd345/cmd/godoc/x.go#L27-L50.

Remove workaround for https://groups.google.com/forum/#!topic/golang-nuts/9AVyMP9C8Ac
since it has been fixed upstream in Go 1.10.