Add a test infrastructure for tag parsers
Import all test cases from upstream CTags that work for us

The test results were auto-generated and not manually checked, so they
may be inaccurate.  They should be fixed if appropriate if they start
to fail, e.g. when modifying the relevant parser.

CTags' tests that didn't pass weren't imported, but probably should be
added an the relevant parser fixed.
Improve error log when a tag parser test fails
Merge branch 'ctags-tests'