This extra check was needed or every technique would get filtered, except valid aoe that is. Fixes #7053
Add checks for items, skills and bionics of professions

Addictions are already checked when creating an instance of addiction in profession::load_profession
recipes: check for book-to-learn-from exists and is a book else print a debug message
handle re-definitions of vehicle parts gracefully
handle unknown part types in vehicle prototypes
check spawn definitions in vehicle protoypes

Removed the GUITAR spawn from fire trucks.

The item currently does not exists, can be added later when #1980 gets fixed.
Make map::spawn_item ignore item ids that would lead to a null item on the map.
Fix fuel leak not actually draining tank
Fix water leak spawning bottles of water
Reduce fuel leak rate by 50%
Heavily damaged batteries now self-discharge
show tool charges in item.info
Merge branch 'more-json-consitency-checks' of https://github.com/BevapDin/Cataclysm-DDA into multimerge
Merge branch 'improved_fuel_leaks' of https://github.com/belenos-/Cataclysm-DDA into multimerge
Merge branch 'toolchrg' of https://github.com/cSep/Cataclysm-DDA into multimerge
renames gardening shovel to trowel
Merge pull request #7189 from cSep/trowel

Trowel it is.   renames the gardening shovel.
Merge pull request #2 from CleverRaven/master

pulling in the new stuff, updating my repo