[s2012] Add some doxygen documentation

Signed-off-by: Schmoozerd <schmoozerd@cmangos.net>

(based on commit [12496] - 300f9d7)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>
[s2013] Convert some files to markdown

[ci skip]

(based on commit [12497] - f6e6e9d)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>
[s2014] Fix a typo for spell 37096

Signed-off-by: Schmoozerd <schmoozerd@cmangos.net>

(based on commit [12498] - b3fe1c1)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>
[s2015] Add some safety to some preprocessor defines

(based on commit [12499] - b16927a)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>
[s2016] Remove a few empty lines

(based on commit [12500] - c980fab)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>
[s2017] DBScripts Engine: Support buddy search by guid

* Add new `data_flags` flag SCRIPT_FLAG_BUDDY_BY_GUID (0x10)
If this flag is set, the content of `search_distance` is interpreted as db-guid of the requested buddy

* Also switch most error log output to DB-error log output (though this will include false positives)

(based on commit [12501] - f2ee8c0)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>
[s2018] DBScripts Engine: Allow pets as buddy

Add new flag SCRIPT_FLAG_BUDDY_IS_PET (0x20) that will search not for a normal npc with buddy-search, but also for pets

(based on commit [12502] - 112908b)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>
[s2019] DBScripts Engine: Change behaviour to search for a different npc when using buddy-search

With this an npc buddy will be interpreted as "another npc with entry"

Also toggle command 31 - TERMINATE_SCRIPT to also look only for other npcs of entry

(based on commit [12503] - 5eff81f)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>
[s2020] EventAI: Improve TargetSelection related ErrorLog output

(based on commit [12504] - 17879f2)

Signed-off-by: Xfurry <xfurry@scriptdev2.com>