Parse shorthand refspecs as valid

Relax the ONELEVEL ref naming rules so the refspec parsing code can
ask for 'master' to be considered valid.
remote: dwim the refspecs according to the remote's advertised refs

As git allows you to store shorthand refspecs in the configuration, we
need to do this ourselves.
cmake 2.6 parser bug workaround
Merge pull request #1513 from ethomson/cmake

cmake 2.6 parser bug workaround
don't use uninitialized struct stat in win32
Merge pull request #1516 from ethomson/win32_alternate_nostat

don't use uninitialized struct stat in win32
Merge pull request #1511 from carlosmn/refspec-shorthand

dwim shorthand refspecs for fetch