add test for non-escaping slash in quotes

This caused some concern in the JavaCC version, so I copy the test
here.
support escaped quote in doc string

The documentation string allows a backslash to escape a contained
quote. Update the parser and add a test for supporting this.
test that quotes can contain unicode
combine condition test files

Whether a condition is negative or not is clearly related to whether
conditions are correctly parsed or not, so move the negative tests
into the condition test file. Rename that file and change the comment
so they don't focus on `state`/`impasse`. Then fix the numbers on the
tests that come after the deleted file.