Remove DanaeClearAll() wrapper

Instead, always call DanaeClearLevel() directly.
Remove refinement texture loading code

Was broken some time ago.
Remove refinement texture code for static meshes
Remove refinement texture code for entities
Remove NoRefinement texture container flags

Didn't have any effect anymore.
Remove unused global variable Zmap
Remove global variable ZMAPMODE

Wasn't read anymore.
Add notes to not remove unused flag IO_ZMAP