a bit of an engine mod

to increase variety in car parts. The new 'bigness' property is the
only one that's currently transferrable between car parts & items.
Yeah, there certainly needed to be another 'size' attribute. this one's
variable though, and can mean different things depending on context.
(plating thickness, cc of engine displacement, wheel radius, kilowatts,
etc.)

not ready yet. i just wanted to put what i had out there.
L instead of CC in veh part display

Also taking out long word 'combustion' from part name.
same deal for item types as the prev. commit.

mostly cosmetic. Also updating the struct name
it_veh_part -> it_var_veh_part
Merge remote-tracking branch 'dda/master' into bigness
making compile.
Add water to crafting materials if near water source
a copy/rewrite of consume_item for veh parts

this is to preserve some item properties while ignoring
the weird cases of consume_item.
fixing a misconception that i had about

% operator vs. negative numbers
sort of preserving veh part health

through remove & install processes.
Merge remote-tracking branch 'dda/master' into bigness

Conflicts:
	mapitemsdef.cpp
part_info().power going through part_power

this makes engines with bigness actually have variable power.

also, bumping bicycles. because it's not fair that they have the
same wheels that cars have.
Merge pull request #47 from Voker57/water_crafting

Add water to crafting materials if near water source
Butcher with integrated toolset
Reload ammo with heat from toolset
Weld steel plating with toolset
Reduce toolset power drain when heating
Add side by side item comparison

Select two items from an inventory like window.
Shows name, stats and text from both items on a
split screen.
Return bandages and first aid to inventory when they are applied to a limb to no effect.
wheel variety. 5 types, variable diameters,

and implemented traction stuff.
Re-add craftable 2x4s

They appear to have been removed by commit
e1cd33ad5162f560df53485ac74e900e8a6fb4d0, possibly unintentionally?