Completely removed all conversion steps for Dune 2000

Fixes 
* #2293
* #2345
* #2566
* #3279
* major part of #3298

While this greatly improves the Dune 2000 mod first start experience there are some regressions because not all Dune 2000 sprite features are yet implemented namely

* #2211
* #3113

and I removed many manually photo-shopped sprites and Red Alert dependencies. However with those issues visible everyone can now easily contribute fixes just by editing yaml files which make the d2k mod much more maintainable.