clean-up
Repository.xs: Added merge() method
15-merge.t: Added tests cases for merges
Repository.pm: Added merge() documentation
02-commit.t: Improved racy use of time(). Reduces the likelihood of 'off
by 1 second' test case failures.
Changes: update
Repository.pm: improve merge() docs
v0.30

 - Add "paths" checkout option (GH#23) (thanks, @jacquesg!)
 - Various fixes to make it possible to build with MSVC
   (GH#24, GH#25, GH#26, GH#27, GH#28) (thanks, @jacquesg!)
 - Repository -> remotes() now returns a list like branches() and refs()
   (incompatible change)
 - Repository -> tags() now returns a list like branches() and refs()
   (incompatible change)
 - Add Commit -> summary() method (GH#32) (thanks, @jacquesg!)
 - Add new Repository methods (GH#33) (thanks, @jacquesg!):
    + Repository -> state()
    + Repository -> state_cleanup()
    + Repository -> is_shallow()
 - Add new clone options (GH#34) (thanks, @jacquesg!):
    + "remote_name"
    + "checkout_branch"
    + "ignore_cert_errors"
    + "disable_checkout"
 - Update to libgit2 426d845
 - Move Blob/Tree -> is_blob() and -> is_tree() to XS
   (GH#36) (thanks, @magnolia-k!)
 - Add Repository -> new() (GH#37) (thanks, @jacquesg!)
 - Add Remote -> create_inmemory() and Remote -> ls()
   (GH#37) (thanks, @jacquesg!)
 - Add support for more callbacks for:
    + Remote -> callbacks()
    + Repository -> clone()
    + Repository -> checkout()
   (GH#39) (thanks, @jacquesg!) (incompatible change)
 - Add Repository -> path_is_ignored() (GH#38) (thanks, @jacquesg!)
 - Improve Repository -> status() (incompatible change):
    + It can now return the statuses of multiple files (GH#29)
    + It can now detect file renames (GH#30) (thanks, @jacquesg!)
 - Improve Repository -> diff() and Tree -> diff(), they can now take options
   and flags (GH#42) (thanks, @jacquesg!) (incompatible change)
 - Add Signature -> default() method (GH#43) (thanks, @jacquesg!)
 - Repository -> reset() now takes an %opts argument, which can also be used
   to specify the entries that should be updated (like "git reset -- file")
   (GH#44) (thanks, @jacquesg!) (incompatible change)
 - Reference -> target() now takes an additional optional parameter $new_target
   used to change the reference's target (GH#47) (thanks, @jacquesg!)
 - Add Index -> has_conflicts() and Index -> conflict_cleanup() methods
   (GH#46) (thanks, @jacquesg!)
 - Add Repository -> merge() method (GH#31) (thanks, @jacquesg!)