Created world.lua "can object spawn at" check functions

Because lava holes are objects which spawn instead of being
placed this commit must implement the object spawn checking
function: world:wouldNonSideObjectBreakPathfindingIfSpawnedAt()

This new function performs the required spawn checks by calling
four new functions for each test which allow these tests to also
be called in setBluePrintCell() when objects are being placed:
+ world:areFootprintTilesCoardinatesInvalid()
+ world:willObjectsFootprintTileBeWithinItsAllowedRoomIfLocatedAt()
+ world:checkFootprintCellsTileIsBuildableOrPassable()
+ world:wouldNonSideObjectBreakPathfindingIfSpawnedAt()

So this commit must also modify UIPlaceObjects:setBluePrintCell() by moving the
code for these tests into the new test functions.
Implemented Hell Deaths

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

2. app.lua:
Modified afterLoad(): So that the gates_to_hell object will be added to a world's objects list when its from an old saved game.

3. die.lua:
a) 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 for males unless there's enough space.
b) +action_die_tick_reaper: Makes hell deaths happen.

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

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

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