Resolves #677 - Overwriting a buffer now works correctly (you no longer ...

...have to clear it first). This was due to a bad link (one missing '=' after the buffer's num parameter.

Resolves #730 - The dna-modifier window will not refresh if you move away from the console whilst it is busy pulsing a dna string. It will close instead.

Reduced irradiation multiplier due to (continued) complaints
Increased accuracy.
Spoon-fed-station13 :baby_bottle:

Modified   code/game/dna.dm