[z1961] Implement new conditions system

Tree-like design idea by Faramir118, thanks for that!

* Add `conditions` table to store conditions.
* REPLACE current handling of conditions for the *_loot_template tables
  Convert the old conditions in *_loot_template to the new system by SQL-Queries
* ADD support for new conditions to gossip_menu and gossip_menu_option.
  If for these tables no condition_id (new system) is provided, the old conditions will still be used
* Add a small helper python script to contrib/convertConditions, see README there for details
* Add new command to reload the `conditions` table (.reload conditions)
* Add two Meta-Condition types CONDITION_AND (-1) and CONDITION_OR (-2) which are used as:
  value1 (as condition_entry) AND / OR value2 (as condition_entry)

  With these meta-conditions it is possible to create tree like and very complicated combined conditions (like HasAura && (HasItem || HasQuest))

NOTE about conversion:
For easier convertion all the old table data is still preserved, but will be removed eventually (within a circle of the moon approximately)
The python script will not create an optimal initial fill of the `conditions` table. You might want to tweak it manually or suggest some optimized algorithm :)

Signed-off-by: Schmoozerd <schmoozerd@scriptdev2.com>
Signed-off-by: Nighoo <nighoo@gmail.com>

(based on commit ccfeefb)

(cleaned version of 274a2b0)

(based on commit [s1549] - c194b44)