New interface for xml file operations.
Added pugixml to cmake scripts.
Added PugiXmlFileHandle.
Fixed some compiler errors.
Added PugiXmlTree and fixed some bugs.
Update DEPENDENCIES

Added dependency entry.
Test xml for loading classes.
Fixed cmakeList.txt.
Fixed bugs in xml interface.
Update scripts/levels/default/Value.xml

Improved xml structure
Update scripts/levels/spaceinvaders/Concept.xml

Improved xml structure.
some fixes.
Merge branch 'master' of https://github.com/wITTus/Brute-Force-Game-Engine into LoaderRefactoring
Merge branch 'LoaderRefactoring' of https://github.com/wITTus/Brute-Force-Game-Engine into LoaderRefactoring
added loader test
Added some typedefs to make code more human readable.
Added test for childList.
additional tests for new loader code.
Added elementData method.
fixed elementData function
enhanced test for elementData function.