Notify Feature can be easily abused

[sam (Sam Saffron)]

@Noah

For each trust level, they should be limited to how any many people they can notify daily, this will help keep this feature in use & and will also prevent people being spammed by this feature.

I do support this, @codinghorror how do these numbers sound for defaults:

TL0: zero
TL1: 6 notifications max 2 notifications per user
TL2: double
TL3: double again