Drop assembly ETG code

[ThibaultLemaire]

Pros

• Less code
• Less preprocessor directives and compilation params
• We could compile ETG.c with optimization on

Cons

• In a sense it's losing code
• I can't say for sure that won't break some platforms that were supported before
• Poorer performance ? (compiler optimizations might balance that out, I really don't know. And by the way, it's not like performance is an issue with current hardware.)