Fix regular expression. Adding the "|" operator to Token to allow for String declarations.
Adding regression test for lexical extension.
Revert "Adding regression test for lexical extension."

This reverts commit 9f3e097468c458e6a42ea038d28da6af5a3d1556.
Adding unit test instead of ktest.
Merge pull request #317 from kframework/lexer-fix

Fix regular expression. Adding the "|" operator to Token to allow for