Cursor moves and kills ducks, but only from side

Changes:
1. Added the Target Image ROM
2. Moved to Erase, move and draw mechanism
3. Solved problem of extra pixels when moving at speeds greater than 1
4. Cursor moves within boundaries to kill ducks
5. Recycles a cycle by skipping if duck is killed.

Bugs left:
1. !st column of any Duck image from ROM
2. Moving at speeds greater than 1 leaves a trace at the end, when
boundary of screen is reached
3. Target cursors leaves a trail in the first row
4. Cursor erases through ducks if killed in any way except right side
(or moving direction) and freezes if killed when cursor is exactly on
image