Add struct item_data, mob_db and mob_data for plugins

http://hercules.ws/board/topic/7161-plugin-missing-hook-to-struct-item-data-and-mob-data/
Remove plugin data in item_data destruction.
Move mob_db deletion into separate function.
Remove plugin data in mob_db destruction.
Remove plugin data in mob_data destruction.
Add function for reading custom itemdb fields.

This functions called after reading normal fields and after
adding item to itemdb.
Update HPM hooks.
Merge pull request #416 from 4144/plugext

Extend plugins support in item_data, mob_db, mob_data
Fixed Bug#8458
-http://hercules.ws/board/tracker/issue-8458-sgs-running-and-gm-hide/?gopid=24216#entry24216

Signed-off-by: malufett <malufett.eat.my.binaries@gmail.com>
Follow up@772cb2b111973c0c749e505ffd2685bb67e887bd

Signed-off-by: malufett <malufett.eat.my.binaries@gmail.com>
Allow use constants in item_db.conf for int fields.
Merge pull request #418 from 4144/itemdb

Allow use constants in item_db.conf for int fields.
HPM Hooks Update

Signed-off-by: HerculesWSAPI <Hercules@efficiently.awesome>
Fixed an issue in the Doha's Secret Orders quest

- Follow-up to bba3e690. Issue caused by an improper fix in commit 46f88c20.
- Fixes bug 8425, special thanks to Ink, Michieru
  http://hercules.ws/board/tracker/issue-8425-dohas-secret-orders-bug-since-the-new-questprogress-command/

Signed-off-by: Haru <haru@dotalux.com>
Removed deprecated commands setriding, checkriding

Follow-up to c6f102e

Signed-off-by: Haru <haru@dotalux.com>
Removed deprecated commands setmadogear, checkmadogear

Follow-up to b3aef69

Signed-off-by: Haru <haru@dotalux.com>
Removed deprecated commands checkdragon, setdragon

Follow-up to a852bdd

Signed-off-by: Haru <haru@dotalux.com>
Marked 'menu' script command as deprecated.

Note: Scripts in npc/custom haven't been updated to remove usage of
said script commands yet.

Signed-off-by: Haru <haru@dotalux.com>