sort issue by name

[willnorris]

request from @rsc (Go lead):

I think my #1 issue request for Github would be to support sorting issues by title text in addition to their current various time-based sort options. This is trivial, and for Go we make sure the titles have scoping prefixes identifying what they're about, so sorting by title would group related issues. (I have a command-line issue navigator that already sorts by title, but every time I visit the web interface I miss being able to do the same.)