Added explicit documentation on synchronisation.
Minor code tidying and typo fixes.

Fixes issue 4344.

Change-Id: I92b691de235cb5da1ca83133cb6eac451c5973bd
Reviewed-on: http://gerrit.dmdirc.com/1452
Automatic-Compile: DMDirc Local Commits <dmdirc@googlemail.com>
Reviewed-by: Gregory Holmes <greg@dmdirc.com>