Make THDR TYPE_ENERGY again, so it goes in photon map

Will simplify checking for excessive stacking
Prevent solid particles stacking in E-Hole

Such as occurs when cloning a solid in E-Hole
Create BHOL when particles are stacked excessively
Run stacking check less often

But force it to be run after loading a save so that really extreme
numbers of stacked particles form BHOL immediately
Avoid stacking in INVS and FILT, and fix pressurised INVS graphics

Collisions now always work for particles inside INVS and FILT, so
particles don't stack (just a single particle on top of each INVS/FILT).

Pressurised INVS was being drawn using PMODE_FLAT (with no alpha
blending), which sometimes hid particles inside INVS.

Also limit BHOL tmp value to make sure it saves correctly.
Revert "Make THDR TYPE_ENERGY again, so it goes in photon map"

This reverts commit 8b20bfd764308fddc1280b8a9d030e77503d0b0c.

TYPE_ENERGY makes THDR move like photons, and means adjacent particles
don't conduct as much heat from it (since the heat conduction code only
looks for particles in pmap, not photons).

Heat transfer could be fixed by increasing THDR's heat conductivity, but
gas or powder movement is probably better than photon movement for THDR.
Prevent THDR from counting towards stacked particle limit
Remember ctype when cloning lava
STOR should not conduct heat
Remove sdl_scale from update_O2

Particle coords are not affected by sdl_scale, only mouse coords
Make ambient heat convection work a bit better

Previously, it was comparing the temperature of the current cell to the
average of the cells around it (plus some advection affecting the
average, but that makes no difference if the air starts out stationary),
and basing the velocity change on this temperature difference.

If the cell below is hotter and the cell above is cooler, the air should
rise. But in this case, the average of surrounding cells tends to be
near the temperature of the current cell, so not much happens.

Just using the temperature difference between the current cell and the
cell above makes convection work a lot better.
Update to EXOT that makes it permeable to neutrons as well as electrons. Neutrons cause a water>distilled water spread that enables EXOT's copy function, at its original speed. Electrons reset mode, but not tmp2. Trippy monochrome colors for copy mode.

Conflicts:

	src/elements/exot.c
Updated FRZZ element to behave somewhat like SNOW, since it has roughly the same physical properties. Also changed its element description, since it actually appears on a menu. Leftover FRZZ will eventually become ICE if touching ICE with FRZW ctype.
Added a tmp=1 flag to PLNT so that VINE will actually function like intended when VINE_MODE is disabled. Plant touching wood is unaffected, but vine that touches wood will grow.
Version Increment
Minor improvement to text wrapping

When text flows onto a new line, don't put the space between words at
the start of the new line.
Fix bug with the improvement to text wrapping

Cursor was sometimes in the wrong place
Move INST flood fill into a separate function

Since there were so many if statements for INST in flood_parts. Also, allow
INST inside walls to be sparked.