#15 spy detection needs work

[Markus Armbruster]

Each `spy' or `lookout' gets a new chance to detect
spies. So players repeat `spy *' a bazillion times.
Chore. Silly.

`sneaking on shore' is a suicide mission (90% failure).
Feels wrong. Maybe the chance should depend on number
of military and civilians. Scale civilians by
happiness factor? Do something similar for marching?

[Markus Armbruster]

Logged In: YES
user_id=596270

All spy actions have a (110-eff)/100 chance to get caught,
except `sneaking on shore'. I'd like to have all spy
actions use a common base chance formula, with suitable
modifiers for difficulty. E.g. if some action is deemed
twice as hard as normal spy actions, give it half the base
chance perform it undetected.

[Markus Armbruster]

Sneaking ashore succeeds with probability (110-eff/2)/100 since commit 4b3b133, v4.4.0.