Autocomplete / CallTips for QScintilla

This is based on the scintillaeditor branch and is mainly here for discussing how we want to use the Autocomplete / CallTips feature that is provided by Scintilla.

Things to decide:
- How to format the CallTips display? What information to present?
- What options are needed
  - enable/disable AutoComplete
  - AutoComplete threshold
  - enable/disable CallTips
  - ...

ToDo:
- [ ] Move data to separate text file, currently it's just in code