Cleaned whitespace
item#typecast

The typecast methods now more flexible and you can define additional
typecasting typecasters without adding to the same method.
More documentation about types conversion
Removed the un-needed block for NilOrAlreadyConverted
Removed Types and #primitive_type method
Clean up paths in #from_xml_node for types and xml content
Spec - cleaned up unused creation in Attribute Spec
Merge branch 'refactor-typecast'

Conflicts:
	lib/happymapper/item.rb