patch from John Ehresman to autocompletion when cancelAtStartpos is false and user backspaces into pre-existing text.
patch from John Ehresman to autocompletion when cancelAtStartpos is false
and user backspaces into pre-existing text.

R1dO/scintilla_clone,R1dO/scintilla_clone,R1dO/scintilla_clone,R1dO/scintilla_clone,R1dO/scintilla_clone,R1dO/scintilla_clone,R1dO/scintilla_clone,R1dO/scintilla_clone