caesar3: Drop some unnecessary files

c3.inf contains the game's settings. It is read (and written to) by theengine, but they tolerate it being missing.

I do not find references to c3map.inf, but I assume it was originally for the map editor settings.

Both the above a non-text files.

language.inf is a readable text file, and contains what appear to be captions for the current folder.

*.ico files are not the game's icon, and are not read by the engines.