Remove stub functions?

[malespiaut]

Hello,

I wanted to start fixing all -Wextra warnings, but some of them are about unused function parameters, because the functions are stubbed.

Is it necessary to keep some functions like UL_ChangeDrive() (in rt_util.c)?

[fabiangreffrath]

We should get rid of as many distractions and indirections as possible.

[malespiaut]

On my way to clean the code up, once again!

[fabiangreffrath]

I am even considering to remove the 800x600 resolution support. It's an odd resolution (neither an integer multiple of 320x200 nor 320x240) and strictly had no place in a game of this time. Also, it requires too many exceptions in the code.

[malespiaut]

I've never been a fan of higher resolutions for ROTT. So I'm not the one who's going to complain about that!