Blinking cursor should blink on immediately after a keystroke.

[unbibium]

Right now if you move the cursor while it's blinked off, it'll be invisible until it blinks on naturally. This makes it hard to track the cursor.

[unbibium]

The C64 screen routines solved this in two different places: at $E5CD, it would turn cursor blinking off if the keyboard buffer had any contents. If a character was input, it would check the blink phase to see if it had to restore the character under the cursor. If it did, it would call $EA13, which set the blink timer to 2 frames -- this step was being skipped, because the port doesn't call $EA13 since restoring the character and color both take only one SET.

I added the blink timer setting to this routine, and behavior seems to have improved, but it's still not quite right.