Added optional config ini file for configuring key mappings used by Edit Mode.
Fix PlayMode_Rave condition for turning off Life and Combo graph on Evaluation.
Merge pull request #370 from kyzentun/mappable_edit_mode

Merging because I want to make sure this is in the next nightly build and it worked when I tested it.  It has no effect on people who do not create the special config file, and will not create one if one is not found.
Fixed mistake that caused steps from non-ssc or non-sm files have blank StepsTypeStr.