Parser should handle invalid proxies nicely

[csmith]

At the moment it throws an exception and reports this an as error, this should at the very least be a user error.

java.lang.IllegalArgumentException: Invalid Proxy — parser.irc.IRCParser.newSocket(IRCParser.java:798) 
java.net.Socket.<init>(Unknown Source) 
com.dmdirc.parser.irc.IRCParser.newSocket(IRCParser.java:798) 
com.dmdirc.parser.irc.IRCParser.findSocket(IRCParser.java:884) 
com.dmdirc.parser.irc.IRCParser.doConnect(IRCParser.java:914) 
com.dmdirc.parser.irc.IRCParser.run(IRCParser.java:1001) 
com.dmdirc.parser.common.ThreadedParser$1.run(ThreadedParser.java:49) 
java.lang.Thread.run(Unknown Source)