Remove some unnecessary parentheses
Minor: named params
Capitalize for consistency
Simplifiable operation on collection
Simplify function
New xxf:client-id() function
Minor: clearer name
Unneeded assert
Modularize FormRunner object
Implement #1094 "Use separator other then "$" in ids"

- use rarer Unicode character
- fr:error summary
  - relied on effective id format
  - now uses native Scala method
  - simplified and complex functions are now in Scala
- fixed other hardcoded uses
Refactor Form Runner and FormBuilderFunctions

- FormBuilder is a single object which aggregates traits
- moved FormRunner-specific functions to FormRunner
- from XForms and XSLT, use fbf and frf prefixes
- DataModel and ToolboxOps remain separate for now
PDF template: move functions to Scala
New fr:tabbable component

This depends on #1094.