Merge topic 'SIMPLEITK-327_AddGitBasedVersionInformation'

6cff964 SourceVersionVars was defining empty variable.
e3febc2 The _GIT_VERSION variables for patch should come from tag
b4fd739 BUG: RC part of tag not extracted correctly
a00b9a4 BUG: CSharp's AssembleVersion must be of the format N.N.N.N
Merge topic 'UpdateSwigDocs'

7b76618 Updating documentation in .i files from SimpleITK doxygen.
Merge branch 'master' into next

Change-Id: I6f94da6cd22fbf3fc57883ab0cd901a08759c2c3