Some fixes and optimizations.
Added applying transform to 'rect' element, when possible.
Fixed font-size attribute removing.
Added em/ex units converting.
New double to QString converting algorithm. x4 faster then original.
Fixed CDATA processing.
Fixed text removing (that's why 0.65% 'better' cleaning in previous
commit...).
A lot of code refactoring and code structure changes.
15% faster