* Fix name collision for string concat to text block cleanup

- add new method ASTNodes.getAllLocalVariablesInBlock() to find
  all variables including ones declared after the string concat
- fix StringConcatToTextBlockFixCore to use new method for name
  collision checking
- fix StringConcatToTextBlockFixCore.escapeTrailingWhitespace() to
  only escape the last white space character instead of all of them
- fixes #1238