[colm] go grammar results in huge output file

[adrian-thurston]

There are two factors leading to huge output files in go.

1. using utf8 directly in the lexer <- affects more
2. patterns for inserting semis

Would be nice to have an additional pass on the input before going to the parser that allows transformations. The same technique could be used both for transformation from utf8 to unicode and for inserting semis. it would be a chain either before or after lexing.