Resolves #552

Sends associated lines through ReadLine() rather than PutIRC(), this allows the user to alias to znc core or module commands as well.
The issue is not with exposing it to the rest of the module (which is harmless, btw), but with sharing the value between all instances of the module (the module could be loaded for multiple users or networks)
Let's say the module is loaded on networks "net-1" and "net-2". On "net-1" there is an alias `foo` which sends `znc jumpnetwork net-2`, and `bar`. On "net-2" there is an alias `bar` which does something.
Client is connected to "net-1" and sends `foo`. With a shared variable `bar` won't trigger.

Well, this is a global variable now.