Fix some logic errors in the configuration parser.
Cleanup.
Fix 'DefaultTooltip'.

Obviously it contained a memset() call, which is really bad for non-POD members... thus leading to a crash in the std::basic_string destructor.
More renaming and cleanup.
Cleanup.
Cleanup.
Rename Area::Clone into Area::CloneArea.

This commit also makes Area an abstract class, by making the destructor pure virtual. Also, some more cleanup still.
Simplify ConfigGetMonitor.

All that pointlessly confusing code flow goes away now that server.monitor is an std::vector.
Cleanup.
More renaming and cleanup.

Moved `visible_taskbar()` so to be a member function of Panel, which is clearly where it should belong.