Writing nested modules explicitly
Removes constants; Moves classes definition from other classes to modules
Removes BlockEvaluator
Removes ObjectUtils
Removes DocumentBuilder; Uses Package::DocumentBuilder directly
Moves everything related to xml forming to Document module
Moves all constants from Known to relevant classes
Changes ContentBuilder to Root element
Removes ElementList
Moves block eval to Element#initialize

The main goal is to avoid saving block in instance variable as it won't be GC'd 'till object itself is GC'd
Renames mappings to properties; renames properties constants
A little Ruby-style cosmetics
Small comment
Merge pull request #2 from vyorkin/refactor2

My take on decomposition and stuff