added token TkImp, removed TkMain and TkBegin (we dont have a main nor a block statement)
changed Tks as specified in Lexer. Changed functions parsing to only define and only implement, no doing it in a one-liner any more
fixed functions: no Signature data, 2 constructors (StFunctionDef, StFunctionImp), included Declaration in StFunctionDef, fixed print fro functions
including the fix #2 (also trying the fix through commit thing). also adapted design to match new decisions