OnUserAttached is renamed to OnClientLogin and
OnUserDetached to OnClientDisconnect.
This adds some new function with different arguments for the old names to cause
warnings from -Woverloaded-virtual while compiling.
This patch also adds OnClientConnect() which is called when the low-level
raw connection is established. (No SSL-handshake was done at this point yet!)
git-svn-id: https://znc.svn.sourceforge.net/svnroot/znc/trunk@1266 726aef4b-f618-498e-8847-2d620e286838