Add option to change game (and other) paths from absolute to relative

[lmills87]

To increase portability of games collection, it would be useful to be able to change game paths (and all other relevant paths) to a relative structure.

For example:

C:\Users\lmill\Desktop\Metropolis_Launcher\games\KQ1

becomes

.\games\KQ1

It would also be useful to be able to specify helper programs in this manner as well, if that feature is added. That way, the Metropolis_Launcher folder (assuming it contains games and all other relevant files) can be moved from one PC to the next without issue.

[theMK2k]

This is feasible.

TODO:

• integrate a "portable mode" which must be activated
• the portable mode needs a defined root directory
• a placeholder %game_root% will be used in the directory definitions for games/roms etc.
• a placeholder %emu_root% will be used in the directory definitions for emulators
• when "portable mode" is activated, every directory in the database will be analyzed for compatibility with the placeholders, user decides if the mode should finally be activated

[theMK2k]

The %game_root% as well as %emu_root% may well be set as "." by the user when games AND emulators are below Metropolis Launcher's application directory.