Pass event to showMenu on context menu

This is used as a hook to establish if CTRL, shift and Alt keys are down
CTRL, Alt & Shift keys now established natively

Instead of having toggle variables for CTRL, Alt and Shift we are now
establishing if these keys are up/down from the event object passed in.

This means we don't need these flags, it's less code, and more reliable
too as we query if these keys are down from the event hooks.

delKeyDown is also removed though was never really used.
Dimensions now shown under image

The natural image dimensions are now shown next to the image name (now
in bold) along with a note that it's displayed at a reduced size, if it
is.
If ctrlKey, don't openCloseDir

We are selecting files/folders if the control key is down, so no need to
open or close dirs