Make Lings vulnerable to Shock/Cardiac Failure..again

[SgtBriar]

This is a change that was never actually listed in the changelog, but was discussed by Cogwerks in the SA thread and slipped in stealthily. Lings no longer go into shock or cardiac failure and this makes them nigh-on *invulnerable*. This now gives a ling a very sporting chance against groups, whereas before it was its greatest - and one of its only - weaknesses. At the very least, make this invulnerability limited to Abomination form.