newline should accept regex

[candidia]

I have a csv that inconsistently uses /\r\n|\n/ for new lines. This would help clean up the stray \rs left around

[dboskovic]

Interesting. I'm going to add this to gremlin mode scope. I think allowing regex would slow down the lexer meaningfully here and mixed line endings is out of spec. But gremlin mode should be able to recover from all those errors.