Create a default config file if it doesn't exist.
Update man-page and --help.

Remove an obsolete per-game config support. It doesn't work with the
RGUI concept at all and is mostly just confusing.
Don't try to load skeleton config.

Breaks RGUI since it's usually read-only.
Add some more example command lines to man-pages.
Merge pull request #320 from libretro/createconfig

Create default config