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)

ACF6: Make sure player only gets portal gun at the portal sequence, and not a pile full of weapons and ropes

ACF3: Mention mines time in a sequence where it has been forgotten String freeze is maintained, the string is already in stub.lua

ACF2: Fix Lua error spam when Leaks A Lot died in same turn as weaklings, also do other minor tweaks - Grant skip to Dense Cloud and Leaks A Lot again, after refusing the cyborg's offer - Fix flow chart - String freeze is maintained, the new string is already in stub.lua.