ignore the pointer to the menu window when it's NULL
make choose_escape_item and use_escape_item use the item position system, not invlets

both player::use and player::consume use the item position as parameter
Make npc::use_painkiller consume the item by its position (what player:consume expects)
fix item description
gaswarfare book -> textbook_anarch
Merge pull request #6269 from Soyweiser/Migo_speech_rename

Migo speech rename
Merge remote-tracking branch 'illi-kun/item_description'
Merge remote-tracking branch 'origin/master'
Merge remote-tracking branch 'Soyweiser/Boom_goes_the_dynamite'
Merge remote-tracking branch 'BevapDin/fix-some-npc-bug'
Merge remote-tracking branch 'BevapDin/fix-ui-menu-window-crash'