Improved symbol token

: is no longer breaking, rather only brackets, braces, etc. are breaking. This is way easier to remember.

Renamed to SymbolToken (derp)

Made escaping and breaking logic actually work. Added breaking exceptions for -> and =>.
Added modifier label token and reference token to take care of :

Now : doesn't need to be a breaking character

Also added "above" and "below" to keywords (and modifiers) to specify precedence somehow
Small changes to example

'match' is no longer a modifier
more lexer exceptions
This should have been with the last commit
Tests for symbols and new text stuff
Added lookahead check to stop symbol from matching refs

: characters will now break a symbol if it's followed by a letter, number, or underscore (which wouldn't be valid in a symbol anyway).