Split hittable.cfg into two files.

My idea is to make it easier for other module creators to use the Frogatto's hittable.cfg code. I'm in the process of making my module standalone from Frogatto, and hittable.cfg was probably the hardest one to make work. (Because it depends on Frogatto's files/objects in several places.)

Everything that was specific to Frogatto was kept in hittable, while everything that is general has been put in hittable_std. Functions which both required by another general function *and* depended on Frogatto got turned into virtual functions for hittable_std. (And then overloaded in hittable, to keep from losing functionality.) I have kept a few examples from Frogatto in hittable_std.cfg to make it easier to use.

Although I have not tested Frogatto extensively, everything seems to run. (I can't say that for my game, yet, but at least hittable stopped throwing errors.)