Load modules from properties file (by class name).
XML configuration overriding the properties.
Merge pull request #3 from RobSis/master

Configuration improvements
Merge pull request #4 from jakubadler/master

MrowNormalizer implementation (erroneous) + tests
XML configuration rethinked
Keep attributes modifying semantics

Based on http://www.w3.org/TR/MathML2/chapter4.html#id.4.3.2
qa
Merge pull request #5 from RobSis/master

XML configuration changed
Added more tests for MrowNormalizer