Enforced limits on string length and handled the finite nature of integers for number parsing and the construction of the AST.

Include: symbol table for global variables now also includes locations for the first import/export of each known variable.

Testsuite: added test regarding matching the empty string and fixed an issue in the i;ascii-numeric comparator.

Testsuite: added RFC compliance tests for the variables extension and fixed use of wrong default comparator.

Fixed bug in the order of default argument processing. Variable strings were evaluated befor constant strings, which is wrong.