Artillery - Add Rangetable Keybind, Fix remembering last charge

[mrschick]

When merged this pull request will:

• Make 82mm Mortar Ammo visible in the Arsenal and Zeus inventory Editor, allowing individual rounds to be added and removed from inventories without throwing errors (at least with ZEN);
• Add a keybind to open the 82mm Artillery Rangetable directly;
• Fix the last selected charge not being remembered when reopening an artillery rangetable (not just 82mm), it appears this feature was incompletely implemented in the past;

Further improvements for the future:

• Add keybind to open Artillery Rangetable on the closest vehicle, though that would require delving deeper into and probably duplicating some rangeTableOpen code;
• Also allow adding 82mm Rounds into inventories from 3DEN's object inventory selector, no clue which CfgMagazines attributes needs to be overridden for that though;

[LinkIsGrim]

Any side-effects from changing magazine type?

[mrschick]

Not that I can tell, everything appears to function normally, but I'll do some more testing.

[mrschick]

Nope, everything works normally, from assembly to ammo handling, loading/unloading and firing.

[LinkIsGrim]

Tested, LGTM. Further improvements should be done in another PR.