Initial commit for parse_ini_string (intended to check the impact of the changes)

This is a work in progress to check how bad is the parse ini state after all the changes I did.

Note though, that is going to be hard to have 100% parity with `parse_ini_string` (and friends), as their errors in some cases includes the expected state.

Because of issues #45 and #46 I had to modify some tests. And also I added a `phpt` test file that I know need to complete and move to `testing`.