Refactor|Definitions: Relocated Episode and Map Info defs to MAPINFO

Support for the ZDOOM-extended MAPINFO requires that this data is
made available to idtech1::MapInfoTranslator (we can't simply bypass
the translation in games with no MAPINFO in the IWAD).
qmake|Resources: Add MAPINFO defs to the game's base data package
API|Game: Games can now be attributed with a MAPINFO data path

Any definition data on this path will be translated to DED during
game init.
Definitions: Process the game's main MAPINFO definitions first

M_ReadFileIntoString() can now access the virtual file system (FS1).
IdTech1Converter: Updated MAPINFO translation, minor compatibility fixes

When extracting a number from a string ZDoom uses atoi-like behavior.
Also added translations for various ZDoom properties which we now use
in the default MAPINFO data.

Note that achieving ZDoom-compatible MAPINFO behavior is out of scope
for the 1.15 release.

Todo: Revise music song/track attribution.