Update the LIFT parser and migrator for LIFT version 0.15.

The tests were updated (and expanded) as well.  A few compiler warnings were also fixed in passing.
Further enhancements of testing migration to LIFT version 0.15.
Get the overall Palaso set of projects to compile with the changes to Palaso.Lift for LIFT version 0.15.
Fix element name in the LiftField class to match the renamed attribute in LIFT 0.15.  Added the LiftFieldDefinition class.
Tweaked the XSLT for migrating from LIFT 0.14 to LIFT 0.15.
Fix XSL for converting LIFT files from 0.14 to 0.15
Adding .gitattributes and .gitignore files