Changed Lexer's function `lex` name to `tok`
Added more Parser errors.
Minor changes in Lexer.
Added some functions to work easier.
Fixed bug where return in top-level would break the compiler
Calculating offset for fields. (Only records)
Fixed bug of stackScope.
Now we accept Scalar types in print
Calculating unions width (biggest field)
Added 'CatConstant'
initialStack -> topStack
fixed some Prelude imports
Width and offsets calculations completed
Imports, Syling and comments