Properly escaping list separators when printing to SDF.
Removing StringUtil.escape/unescape since their behavior is better captured by quoteString and unquoteString.
Revert "Removing StringUtil.escape/unescape since their behavior is better captured by quoteString and unquoteString."

This reverts commit 52469659906869b58b3d3c056bf9938b55417c7c.
Making more clear the separation between K Strings and the strings used for SDF.
Forgot about the jj files.
Adding some javadoc in StringUtil.
Let's see if maude likes our idea of C Strings escaping.
Again, I forgot about the jj files.
Separating the un/escaping functions into C and K.
Trying to see what happens if I use the apache implementation of the Java escape convention.
Revert "Trying to see what happens if I use the apache implementation of the Java escape convention."

This reverts commit e2d46dc882f36fc4a8df38acb278aa543e17350e.
Making unquote unescape octal values. Also added regression tests.
Added a test for enquoteKString also.
Small fixes... also, unified UtilsTest with StringUtilTest.
Merge pull request #744 from kframework/issue733

Properly escaping list separators when printing to SDF.