Cleanup includes.
MainFile: don't use OTString for version string.
Merge pull request #320 from benma/includes

OTString: forward declare / eliminate
split method processXmlNode
OTMessage: move code to updateContentsByType
Merge pull request #303 from mhamrle/otmessage_refactor_part2

Otmessage refactor part2
cleanup OTAPI_Exec