* Creating a true "const" field type that knows its own datatype
* Removing vestigial .d12 compatibility
* Bugfixes
X12 Field enhancements:
  * automatic segment counting for ST/SE
  * framework for parser provided fields
  * properly coding sontant field types
  * code cleanup
Preventing crash when renedering Segment outside of context of Loop
No need to ||'' since  we use to_s everywhere
Using proper syntax
Merge pull request #1 from eligoenergy/field_enhancement

Field enhancement