Remove svnstat stuff used in Doxygen generation

Change-Id: I9d8db5fae6e0c99d59fcb9a43d7ed4aab953c300
mwdocgen.php: Implement --version option.

So that the job that runs it can pass along what it should
display (e.g. branch, tag, hash etc. whatever is appropiate
for the context of that run).

Change-Id: I1d5b6266e49a71672b0a53069e6ea6bb4658c3d2