Fix bug in ZoomToggle, pass visualmode() instead of "v"

- Also fix License filepath in header
Change 2nd argument in NoZoomZoom from jumpback to zoom_out
Remove keepjump command when entering zoom or original buffer

- If the jumplist isn't modified, then a user who jumps to another buffer while
  zoomed in and then tries to jump back will not return to the zoom buffer,
  which is unintuitive.  Same thing happens immediately after zooming back out.
Change <Plug> mappings to noremap and add default mapping
Add ReselectLastRegion function and mapping
Add default MazdaToggle mapping for visual mode too