Update to the last rust.

Option `map` method does not give a reference to the wrapped element any more.
It should be replaced by `as_ref().map`.
Merge pull request #38 from sebcrozet/option

Update to the last rust.
Add .travis.yml
Added linking configuration for win32.
Merge pull request #39 from ameyp/master

Added linking configuration for win32.
Fix linking for OSX and Linux

…hopfully? Used -lglfw3 on OSX, added -lGL for linux builds.
Revert previous change to linking on OS X, and add a note and FAQ entry for Homebrew users.
Return an Option on window creation