Fix crashes with SelectionText instances that did not have \0 terminators.
Fix crashes with SelectionText instances that did not have \0 terminators.

windoze/scintilla,windoze/scintilla,windoze/scintilla,windoze/scintilla,windoze/scintilla,windoze/scintilla,windoze/scintilla,windoze/scintilla