- minor cleanups reported by CppCheck v.1.79

- fix exception - reported in notepad2-mod pull request (Crash fixing. XhmikosR#172), which has been rejected there,
  but I was able to reproduce it in VS2017 debug mode (initial defaults for exception handling).
  (XhmikosR#172)

- incorporate changes from  notepad2-mod from v.4.2.25.995  to  v.4.2.25.998
  (one fix,  the other changes we have done before already)

- Change shortcuts for the following actions:
  (-) Toggle Transparent Mode:  moved from Ctrl+0  to  Ctrl+Numpad_*
  (x) Reset Zoom: Ctrl+/ change to Ctrl+0      ($v_5.0.26)
  Additional Accelerator Keys, as suggested by (XhmikosR#197)
  (+) Toggle Line Comment : in addition to Ctrl+Q add Ctrl+/  with same functionality
  (+) Do Stream Comment : in addition to Ctrl+Shift+Q add Ctrl+Shift+/ with same functionality
  believing new shortcuts are more convenient and more widely used, aren't they?