Strip prefixes from multi-line aliases.

When migrating make sure that existing multi-line aliases get
command chars (and any following silence chars) removed, rather
than just doing it from the first line.

Change-Id: I08b7081cd3f582901909001586048b209acbfa31
Fixes-Issue: CLIENT-512
Reviewed-on: http://gerrit.dmdirc.com/3645
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Remove old alias wrapper.

Change-Id: I52684c3c812d7fc3c13cde8a08d1f4bc65a6f821
Reviewed-on: http://gerrit.dmdirc.com/3646
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>