Fix frontend not sending script param if empty

Fix Battialion script showing “Round 0” at start

Fix host not re-sending ammo scheme after editing an existing ammo scheme This caused clients to start with an incompatible ammo loadout.

Update Polish tips and mission map descriptions

Update changelog regarding wrap world edge bugs

Add Polish translation for campaigns and new missions

Update pl.txt translation file

Backed out changeset c162995831d8

Backed out changeset 058a5d373e4a

Backed out changeset d08afea02908

Minor pl.txt update

Update and complete Polish frontend translation

Fix Hedgewars going into suspension mode (game freezes) when windows got minimized

Update Polish translation (frontend, 3 strings missing)

Fix broken cancel button on the login window (bug #373)