[Feature] Allow any spawn2 spawned mob to path while zone is idle if new flag is set. (#1339)

* Changes to allow any spawn2 to be marked to path even when zone is idle

* Fixed for Kingly review of PR

Co-authored-by: Noudess <noudess@gmail.com>

utils/sql/db_update_manifest.txt

@@ -418,6 +418,7 @@
 9162|2021_02_17_server_scheduled_events.sql|SELECT * FROM db_version WHERE version >= 9162|empty|
 9163|2021_04_17_zone_safe_heading_changes.sql|SHOW COLUMNS FROM `zone` LIKE 'safe_heading'|empty|
 9164|2021_04_23_character_exp_modifiers.sql|SHOW TABLES LIKE 'character_exp_modifiers'|empty|
+9165|2021_04_28_idle_pathing.sql|SHOW COLUMNS FROM `spawn2` LIKE 'path_when_zone_idle'|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/2021_04_28_idle_pathing.sql

@@ -0,0 +1,13 @@
+-- Add new path_when_zone_idle flag to allow some spawns to path in empty zones
+ALTER TABLE spawn2 ADD COLUMN path_when_zone_idle tinyint(1) NOT NULL DEFAULT 0 AFTER pathgrid;
+
+-- Update spawns that used to path in empty zones because of their grid type
+-- to behave the same using the new mechanism.  The code that checked path grid
+-- types has been removed as it was coincidentally coupled to idle movement.
+-- The new flag path_when_zone_idle is the new mechanism, and allows any moving
+-- mob, not just those on grids, to path while the zone is idle.
+UPDATE spawn2 s 
+LEFT JOIN zone z on z.short_name = s.zone 
+LEFT JOIN grid g on g.id = s.pathgrid AND g.zoneid = z.zoneidnumber 
+SET path_when_zone_idle = 1 
+WHERE pathgrid != 0 AND g.type in (4, 6)