Allow HP/MP steal powers to work on the final blow

Closes #777

If an entity is killed with a power that steals HP or MP, a percentage
of that enemy's HP before dying is taken (as opposed to a percentage of
the damage delivered).
Simplify calculating steal_amt
Add Morel Bérenger to the mailmap file
Simplify getVideoModes()

Video modes are now stored in a vector instead of a C-style array. In
addition, we do better checking for duplicate resolutions and explicitly
include the mod-determined minimum resolution now.
Obey MIN_VIEW_W and MIN_VIEW_H when getting video modes
Merge pull request #806 from stefanbeller/mailmap

Add Morel Bérenger to the mailmap file
Merge pull request #807 from dorkster/config

Simplify getVideoModes()
Merge pull request #803 from dorkster/steal_hpmp

Allow HP/MP steal powers to work on the final blow