techs_en_US has the descriptions, techs.dat has the effects. Everything
is in plaintext, with effects handled through techs.py. Ignore techs.pyc.
Note that anything with a "new" effect will need to be coded in techs.py.
Okay, base.py is where it's actually used, and it's a modifier to that
group's chance to detect the base. Their chance to detect the base is
multiplied by discover_bonus/10000.
In a game on Normal, discover_bonus starts at 10000, so the chance to
detect the base is multiplied by 1. After a discover_public | 1000
tech, their discover_bonus is 9000, so the chance to detect that base
is multiplied by 0.9.
Very Easy: (before) 7000, *0.7 (after) 6000, *0.6
Impossible: (before)15000, *1.5 (after)14000, *1.4
In other words, discover_public | 1000 reduces that group's detection
modifier by 1000 basis points
(http://en.wikipedia.org/wiki/Basis_point), or 10 percentage points.
-FM