Minor: import
Minor: Scala method
 ScalaUtils improvements

- improved split function taking CanBuildFrom
- combineValues: use Nothing
- comments
Fix #889 "Non-relevant group around <li> with AVT doesn't place xforms-disabled"

- move XXFormsAttributeControl to Scala
- when attribute is class, output class diffs
- clarify escapedExternalValue method names
Move XFormsTextareaControl to Scala
Minor: comment