Added token printing option & abort nil codegens
Fixed extra tokSpaces being emitted.

If "binary"/"unary" was directly followed by a rune, lex would still
emit a space token of zero length.
Bugfix: Set and check for -tok flag
Lexer operates on a queue of files, interactive mode broken
Partial fix
Fixed interactive mode.
Added non-interactive mode
API clean ups
Codegen name cleanup
Bugfix: stop parsing once token chan is closed.
Parsing comments
Skip statements with failed codegen
Better behavior for closed token channels
Refactored token & ast printing into goroutines