Crash if password entered as empty string

[Andy Collins]

When calling the Connect() method in the IrcClient class, a parameter that implements IrcRegistrationInfo must be supplied. Using the IrcUserRegistrationInfo and supplying Password as an empty string will cause an unhandled ArgumentException in the CheckTrailingParameter method in the IrcClient class.

The exception is quite obscure and doesn't actually reference the password property of that particular class however, but once I changed it to a non empty string the issue dissappeared.

[Alexander Regueiro (alexreg)]

This is due to the fact that the code handling the sending of raw IRC messages insures that no parameters are null-length. I've decided it's probably best to allow zero-length trailing parameters, thus this exception will no longer be thrown. (Specifying a zero-length password does however make the server complain by replying with an ERROR message.)