Fish buff

This makes morale bonuses noticeably easier to get as a Fish.  Still not
perfectly intuitive.
Water flags

For all the fishfolk out there who have trouble finding gear.
Replaces doubled 556 entry with two types of 40mm grenades.
MOAR BULLITZ
MOAR 556!
misc *_group fixes and dehackifications

mongroup: provide non-autovivicating means of validity checking.
item_groups.json: guns_with_ammo boolean to replace hard-coded if group == "livingroom" || "behind_counter"
mapgen place_spawns/items: implement the above and _whine_ instead of spitting out null_item or who knows what
item factory load: use global body_parts string-to-int map, nuke
set_bitmask_by_string(...) as it was only used by set_flag_by_string(...),
and casting body_parts to map<Item_tag, unsigned> no workie.

Also eliminate std::string init frenzy via const std::string & args
nuke-a-comment(tm)
json(array|object).throw_error("string"); what it says on the tin
Fix memory access violation
add some l10n fix
Create JSON_FLAGS.md

This file is where flags used in json files will be documented.
Merge misc. fixes.
Merge disease segfault fix and i18n fixes.
Merge pull request #4745 from KA101/WaterFriendlyText

Water flags
Updated.
Fix looking around.
JSON_FLAGS.md - First round of flags.

This is the first round of flags to be added to JSON_FLAGS.md. Being
added as multiple commits instead of one singular update when done, to
be able to see how Github is parsing the file.
fallthrough for MilFood

Makes the rations a bit more likely, I believe.
Don't show the sound indicator while deaf.