Screen blending merge ratio fix
Screen blending merge ratio fix
History overlay cosmetic bug fix and test case update
doc: updates instructions

More dependencies, and the information moved to the doc/develop folder.
Replaced relative stage movement with absolute movement on Overview mouse clicks. (Relative movement was  given weird results, because the user could click a new position while relative movement was already taking place)
Merge branch 'master' of vpn.delmic.com:odemis