Bugfix and clean-up
- Added NPC const
- Added checkdragon() in F_CashReset
- Clean-up books.txt, fortune.txt, card_trader.txt, 3rd_trader.txt, stone_change.txt, quests_brasilis.txt
- Minor fix about Weight in comodo_gambling.txt
- Change to F_GM_NPC function in Mercenary Guild Switch follow up bdab851129ceee57a38ccc9d819b42011ef19fb7
- added Mercenary Switch in gm_npcs.txt list
- change to common green maiden in 2010 Headgear Quests

Signed-off-by: Capuche <capucrath@gmail.com>