PRD-4432,PRD-4503,PRD-4521,PRD-4525,PRD-4526,PRD-4537,PRD-4538: Multitude of formula editor fixes.  Parameter fields are now processed as a string vs individual characters.  Parameter field editor does not dynamically change as user enters embedded functions in their formula.  The parameter field editor displays at the function level when user clicks on function name or inside the parenthesis of the function parameters.  Code review changes and unit tests for formula editor.
PRD-4432: Made inner class private
Merge pull request #110 from pentaho-skarmali/PRD-4432_formula_editor_research

PRD-4432,PRD-4503,PRD-4521,PRD-4525,PRD-4526,PRD-4537,PRD-4538: Formula editor: