Added repository functions.
Updated status for libgit2 0.18 and added doc string.
Merge remote-tracking branch 'woudshoo/master' into 0.18.0

* woudshoo/master:
  Fixed issue with libgit2 INLINE declarations.
  Added some doc strings, small updates to rst files
  Fixed some small issues with changed libgit2, also improved git-target wrapper
  * README.rst: Updated minimum libgit version number to 0.18
  * src/branch.lisp: - Added new function git-is-head,                    - removed non existent funciton git-branch-tracking, and git-tracking 		   - added doc string git-list for :branch 		   - added doc string git-lookup for :branch 		   - added new specialization for git-lookup for :branch
  Added git_index_read wrapper.
  Added git-ls (git_remote_ls) functionality
  Working a bit on remotes and the index.
  Trying to get the new cffi working + adding index-entries
  Fixed test.  I think the new behaviour is correct.

Conflicts:
	doc/repositories.rst
Changed to a new test harness.
Minor documentation changes.
Allow signature times to specified in universal time integer, return a timezone with a signature.
Initialise threading.
Merge remote-tracking branch 'woudshoo/master' into 0.18.0

* woudshoo/master:
  Added two branch functions, improved error reporting in obscure cases. Added potential future tag name lookup
  Added keyword arguments :start :end to git-entries, fixed facilitator in reflog
  Added reflog functionality
  Added more branch/reference methods.  Made error handling more robust.
  Fixed bitfield for status calls

Conflicts:
	src/status.lisp
Better fix for timestamp specifications in integer form.
Added back timezone information. Whoops.
Added back translation of offset.
Fromatting.
Cleaned up repository tests.
Added shorthand function to create one commit and return the test version.
Added more extensive git reference test.
Added better error checking for git revision walker.
Added missing dependency on asdf.
Removed duplicate entry for git_reflog_entry_committer.
Added tests for reference accessors.
Re-factored reference tests to use a fixture.