Attempt to add support for azul3d.org/... import paths.
Try using tools/go/vcs.RepoRootForImportPath.
Remove unneeded subPath, defaultRev code.
Remove no longer needed vcs wrong guess fallback.
Tweak highlighting, don't color brackets.
Make vcsstore host into a flag.
Merge pull request #5 from shurcooL/support-all-import-paths

Support all Go import paths.