Implemented Hell Deaths

Change list
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1. New files:
a) /objects/gates_to_hell.lua
b) /entities/grimreaper.lua

2. app.lua:
< @1259 *Modified afterLoad(): So that gates_to_hell objects will be added to the objects lists in worlds from old saved games.

3. die.lua:
a) @294 *Modified action_die_start(): So that males can either go to heaven or hell. Heaven deaths are less likely because females can only have them and hell deaths won't happen unless there's enough space.
b) @63 +action_die_tick_reaper: Makes hell deaths happen.

4. humanoid.lua:
a) +rise_hell patient animation. @58 @132
b) @499 *Modified Humanoid_startAction(): So that grim reapers with no actions will have the idle action be their default action.

5. patient.lua:
< @938 *Modified afterLoad(): So that patients from saved games older than 84 will be given the new rise_hell animation.

6. world.lua:
a) @175 +newObjectType(): I've created this function so that app.lua can use it to add the new gates_to_hell objects to worlds from saved games older than 84.
b) @538 +checkHellDeathSpawnPoints(): Returns true if there's enough space for a hell death to take place using the spawn points provided as parameters.
c) @551 +lavaHoleUseTileUsable():I put this algorithm into its own function to prevent it from having to be duplicated in checkHellDeathSpawnPoints().
d) @570 +spawnGrimReaperAndLavaHole()
e) @1963 *modified objectPlaced(): I added statements which are required to respond to the spawning of lava holes (gates_to_hell objects).