config: Define infra build cost and mobility use per 100%

config: Define infra build cost and mobility use per 100%

Infrastructure build cost is defined by infra column dcost (struct
sctintrins member in_dcost).  It's the cost per point of efficiency.
In contrast, sector and unit build cost is defined for 100%, by
sect-chr, ship-chr, plane-chr, land-chr, nuke-chr column cost.

Switch to build cost per 100%, for flexibility and consistency:
replace struct sctintrins member in_dcost by in_cost, and selector
dcost by cost.

With cost values that aren't multiple of 100, the build cost may have
to be rounded.  Do this exactly like we round sector build cost: the
amount is limited to money * 100 / cost rounded down, but the money
charged is actual amount * money / 100 rounded randomly.

Do the same for mobility use: replace struct sctintrins member
in_mcost by in_bmobil, and selector mcost by bmobil, with similar
rounding.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>