Some API cleanup

[rurounijones]

There are two areas where we can possibly clean up APIs we are exporting.

1. There is inconsistency in the the use of weaponName string fields and weapon tables in the lua events. We could get rid of the weaponName field and move everything into the weapon table for events that have both (hit/kill events being good examples).

2. For the APIs that take mission filenames (LoadMission, GetMissionFileName) and which take file paths (For some reason) we could do things such as splitting the paths and filenames into two separate fields.

[rurounijones]

Unassigning myself. I still hope to do it but if someone else picks it up before I can get to it then that will work.