Fix issue with heading being incorrectly handled

So we've been doing heading wrong all these years. You will need to run
a script to fix your quests and required SQL to fix DB.

This fixes a ton of random issues with headings and as gives us a better
resolution on headings :P

utils/sql/db_update_manifest.txt

@@ -373,6 +373,7 @@
 9117|2018_02_01_NPC_Spells_Min_Max_HP.sql|SHOW COLUMNS FROM `npc_spells_entries` LIKE 'min_hp'|empty|
 9118|2018_02_04_Charm_Stats.sql|SHOW COLUMNS FROM `npc_types` LIKE 'charm_ac'|empty|
 9119|2018_02_10_GlobalLoot.sql|SHOW TABLES LIKE 'global_loot'|empty|
+9120|2018_02_13_Heading.sql|SELECT value FROM variables WHERE varname = 'fixed_heading'|empty|
 
 # Upgrade conditions:
 # 	This won't be needed after this system is implemented, but it is used database that are not

utils/sql/git/required/2018_02_13_Heading.sql

@@ -0,0 +1,3 @@
+UPDATE spawn2 SET heading = heading * 8.0 / 4.0;
+UPDATE grid_entries SET heading = heading * 8.0 / 4.0 WHERE heading <> -1;
+INSERT INTO variables (varname, value) VALUES ('fixed_heading', 1); -- hack