Added spliceHeader option to c2nim
parse a header file first, then the source. completing a c 'module'
Lex '\xHH' character constants
Properly lex floating constants

digit-sequence? '.' digit-sequence exponent-part?
digit-sequence '.' exponent-part?
exponent-part: [eE] [+-]? digit-sequence
New expression parser

tests pass
for statements support comma expressions