Fixed bug where eval call bumped past all curly braces in an expression.
This was correct until scripts that themselves contain curly braces are eval'd.
Now you can have curly braces inside expressions, because
  1) I added a nested brace parser (with backslash recognition)
  2) I changed the default type of string from Jexl Expression to Jexl Script.
So now the scripts/expressions can have Jexl 2 control structures (if, while, etc...)