Add quite a bit of general QMOD error handling. Errors in QMODs are no longer reported as Launcher bugs.
Handle when all files in a QMOD are wrapped within a top-level directory (this is not as specced, but has happened in the wild—possibly to do with the default behaviour of OSes/specific compression tools when multiple files are selected?)
Ignore any qmod.ini files that aren't in the toppest level of the mod.
Fixes #70