The ircu calls IPcheck_disconnect() only when he kills a client. Therefore, IPcheck_disconnect is the last IPcheck function
which is called on a client. However, this may change.
Therefore, why does IPcheck_disconnect() not remove the FLAG_IPCHECK flag from a client? The IPcheck_connect functions
set this flag, however, the removal is handled manually by the code. This is a bit inconsistent and calling ClearIPChecked() in
IPcheck_disconnect() would make the code clearer.
The problem is, calling any IPcheck_connect function after an IPcheck_disconnect() segfault because of an assertation.