Copy converter package from https://github.com/epabst/triangle.
Switch Converter and ValueFormat to return a scala.util.Try.

This allows the caller to know why it wasn't converted.
Make QualifiedTypes extend StringConvertibleQT if possible.
Update To-do's.
Detect cases where TargetField is passed an Option.
Extract SharedContextHolder from CommandContext.
Fix warnings in GenericConverter.
Fix warnings.
Fix another warning.
Add and use CopyContext in SourceFields and TargetFields.
fix for CopyContext.
fix for CopyContext.
Support delayed update after a copy.
Introduce FieldName to conveniently convert field names to various formats.
Rename StringConvertibleQT.convertToString to convertToDisplayString.

Also rename StringConvertibleQT.convertToEditString to convertToString.
This enables using convertToString for persistence conversions as well.
Add PersistenceConnectionVar.
Making scrud-android compile.

scrud-core at least still compiles.