Merge lp://qastaging/~gue5t/midori/extension-tests into lp://qastaging/midori

Fix memory leaks and logic errors in extension loading and tests

In tests/extensions.c, there are lots of leaks which are fixed with the appropriate unref calls. extension_load is changed to return the extension it loads, so it can be freed. In addition, extension_load is changed to only register the tests when told to do so, because extension_load is called twice to exercise loading an extension multiple times--but GLib does not allow registering the same test twice. This is a correctness fix, and without it running "./tests/extensions -e ./extensions/libYOURFAVORITEEXTENSION.so" fails with a GLib error for every extension.

tests/extension.c also had a few misleading variable names which have been fixed.

In midori/midori-extension.c there's a memory leak where setting->name was only being freed for String or StringList settings, and the setting struct itself was never being freed. These leaks are fixed.