There is no ru_RU language. Just 'ru' as Russian
Russian translation update
Recolor all books systematically

Color code:
Magazines: pink
“Paperbacks” Short enjoyment books (including novels): light cyan
“Hardbacks” Long enjoyment books (including novels): light blue
“Small textbook” Beginner level textbooks and guides: dark green
“Large textbook” Advanced level textbooks and advanced guides: dark blue
Religious books: dark gray
“Printouts” (including spiral-bound and similar) Technical documents, (technical?) protocols, (lab) journals: light green
Other reading material/non-books (use only if every other category does not apply): light gray
Merge pull request #7578 from Rivet-the-Zombie/moar-fixes

More food price fixes.
Document new book color conventions
Remove unused function default_technique_name
Remove unused variable tech_id_lookup

And remove the function initializes it.
Remove the unused enumeration technique_id.
Remove another unused variable: Item_factor::techniques_list
Remove another unused function: item::sort_rank

It is obsolete since the introduction of item categories as a separate class.
ma_technique: add name member to be shown for techniques of items.

Item_factory: when checking item definitions, check the technique, too.

Add simple definitions of the legacy techniques that some items have (WBLOCK, DEF_DISARM, GRAB)

Changed zweifire_off: moved "SHEATH_SWORD" from techniques to flags, because it's a flag.
Merge branch 'book_recoloring' of https://github.com/Wuzzy2/Cataclysm-DDA into merge
Merge branch 'item-techniques' of https://github.com/BevapDin/Cataclysm-DDA into merge
Merge branch 'monter-info-name' of https://github.com/VlasovVitaly/Cataclysm-DDA into merge
Merge branch 'remove-ru-ru' of https://github.com/VlasovVitaly/Cataclysm-DDA into merge
Add tool belt to belted layer
Merge pull request #7588 from MattAmmann/belted_fix

Add tool belt to belted layer
Fixes the prices of some vegetables.
Merge remote-tracking branch 'Rivet-the-Zombie/master' into FrankenMod

Conflicts:
	data/json/items/books.json
	data/json/items/martial_arts_manuals.json
	data/json/techniques.json
	doc/JSON_INFO.md
	src/item.cpp
	src/martialarts.cpp
Merge remote-tracking branch 'Rivet-the-Zombie/more-prices' into FrankenMod