Version 2.35.0

This version contains many bug fixes and improvements.
- Update libxml2 dependency to 2.7.0
- Make GIO and libcroco hard requirements
- Use attributes for deprecations instead of defines
- Many memory leaks plugged
- Bugs fixed: #621636, #630112, #624820, #624835, #581108, #614157, 
              #630733, #473862, #590788, #626559, #663049, #663049