Add else-statement
Use String.concat rather than myconcat
Merge branch 'if-while-for' of github.com:samuel02/RTFM into if-while-for

# By Björn Nilsson
# Via Björn Nilsson
* 'if-while-for' of github.com:samuel02/RTFM:
  adds while and fixed tabbing in AST

Conflicts:
	RTFM-cOOre-compiler/src/AST.ml
	RTFM-cOOre-compiler/src/CoreGen.ml
	RTFM-cOOre-compiler/src/Parser.mly