ENH: Script to generate API differences between two git revisions

The script uses git and ctags to generate a list of classes and public
methods added/removed.
It also lists newly deprecated methods.
The flag --wikiOutput can be used to print the report with wiki markup.

Change-Id: I12a9df100099527599aa5762540e01bd09460c0b
Merge topic 'semantic_diff_ctags' into master

bfed0a05 ENH: Script to generate API differences between two git revisions