added a Tuple based value for the libgit2 version reference (#848)

Author: imbuedhope

docs/general.rst

@@ -39,6 +39,14 @@ library that has been built against. The version number has a
       >>> print(pygit2.LIBGIT2_VER_REVISION)
       0
 
+.. py:data:: LIBGIT2_VER
+
+   Tuple value of the revision version numbers. For example, for the version
+   ``0.26.0``::
+
+      >>> print(pygit2.LIBGIT2_VER_REVISION)
+      (0, 26, 0)
+
 .. py:data:: LIBGIT2_VERSION
 
    The libgit2 version number as a string::

pygit2/__init__.py

@@ -76,6 +76,8 @@
 GIT_FETCH_PRUNE                = C.GIT_FETCH_PRUNE
 GIT_FETCH_NO_PRUNE             = C.GIT_FETCH_NO_PRUNE
 
+# libgit version tuple
+LIBGIT2_VER = (LIBGIT2_VER_MAJOR, LIBGIT2_VER_MINOR, LIBGIT2_VER_REVISION)
 
 def init_repository(path, bare=False,
                     flags=GIT_REPOSITORY_INIT_MKPATH,