Improve OnTakeDamage

[winstliu]

See friagram's post at https://forums.alliedmods.net/showpost.php?p=2146089&postcount=736.

I'm going to try to go with the "better solution".

• [ ] Allow self-damage to go through (aka rocket jumping will now be possible)

[WildCard65]

Well we can keep the big forward(just clean it up and port it to pure sm 1.5) and call 2 seperate forwards in 1 hook (if needed)

[winstliu]

Added a point about rocket jumping.