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/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