Qt: Disable main menu items that don't do anything.

The functionality associated with Capture → Capture Filters, Analyze
→ Display Filters, Analyze → Display Filter Macros, and Analyze →
Apply As Column haven't been implemented yet. Disable each menu item
for now so that we don't play tricks on our users.

Follow our current action naming convention. Rename "Apply as Column"
to "Create a Column".

Change-Id: I01901db05adc897d877f6a0a699e3049b0149b4a
Reviewed-on: https://code.wireshark.org/review/3629
Reviewed-by: Gerald Combs <gerald@wireshark.org>