add limited sprite duplication functionality

Instead of providing colors & sprite matrix, you can instead copy/rotate/flip previous sprites, like so:

    GunUSingle U
    Black Grey Yellow
    ..0..
    12021
    11011
    11111
    .111.

    GunRSingle R
    rotate GunUSingle right

    GunDSingle D
    rotate GunUSingle half

    GunLSingle L
    rotate GunUSingle left

This eliminates tedious copying when there are multiple orientations of an object.

(Also fix a minor case sensitivity issue)