Let the empty string be part of every string. This fixes test cases for replace, has_prefix and has_suffix. Removed redundant check.

Avoid keeping track of if destroy() has been called for objects that
lack destroy().

Each time compile() was called an additional set of rules
was appended. This could be triggered when a zone had
compilation errors.

Also fixes issue with throwing broken errors from compile().

Implement _sizeof(), _indices() and _values() in the generic error class.

Fixes "Index 2 is out of range 0..1." from describe_backtrace().

Use the static program id for Fd/Fd_ref instead of looking up the program. This should perhaps be put somewhere more central.

Conflicts:
	src/post_modules/GTK3/configure.in

Overriding of variant functions now seems to work as intended.

Also adds testsuite test that checks some of the cases.

Added missed flags and did a small code abbreviation. It is worrying that the testsuite did not pick this up.