More vehicle stuff

Added Mark 19 Grenade Launcher and fixed the APC so it was more of an
APC and less of an armored bus. Plans to add Electrified Hull Plating,
Impact Resistant Hull Plating (For plows), and set up turrets to not
blow up their own vehicle. Also added M2 Browning and Mark 19 to the
bunker heavy weapons spawn.
Fixed the Turrets.

And some typos. Also laid the groundwork for the Electrified Plating and
the Impact Resistant Plating.
What Bug?

There is no bug. You saw nothing. No lazy copy/paste that I forgot to
fix properly. You saw nothing.
Pulled Elec and Impact Resist Plating

Because I have no idea how to do it and people are excited enough for
what's done as is.
Removed "Fix"

Don't have the time I thought I did to look for an actual "Fix" Removed
the current one so the work that's done and actually works doesn't "go
bad" and can be merged.
AAPC to MIC

Changed the name of the "Armored Armored Personnel Carrier" to
"Mechanized Infantry Carrier"
Fixes the prices of a few seasonings.
Merge branch 'Vehicoolz' of https://github.com/EkarusRyndren/Cataclysm-DDA into EkarusRyndren-Vehicoolz
Increased HW ammo proportions

Increased chance of 40mm frag/concussive and 50BMG by half the current
chances.  Still not hugely common.

As mentioned in the Git comments, having full-auto weapons using exotic
ammo justifies increasing the supply of said ammo, at least in the "Hey,
here's the good stuff, cut loose!" rare bunker room.
Make ESC exit add/remove hotkey mode.

Add/remove hotkey modes are only partially modal. If you enter one of those
modes and press ESC, it would exit the help screen (or prompt you to save &
exit). With this change, ESC will leave the modal state instead. (Pressing ESC
again will have the same behavior of exiting the help display).
fix scrolling in message window
Merge pull request #7406 from Rivet-the-Zombie/salt-fix

Fixes the prices of a few seasonings.
Merge branch 'esc_from_hotkey_mode' of https://github.com/lucianposton/Cataclysm-DDA into merge
Merge branch 'master' of https://github.com/CleverRaven/Cataclysm-DDA
Don't use conflicting keybindings in the help menu

A hard-coded list of ASCII characters were used in the help menu to select
actions to add/remove keybindings. With this patch, characters conflicting
with other hotkeys aren't used.

Also cleaned up fixed remaining compiler warnings in input.cpp
Use standard UP/DOWN actions to scroll help menu