Previously when any user config file was changed all users would be reloaded. This could be very expensive on installations with thousands of users. Since this triggered when any file was changed it would trigger when any user connected which can be quite frequent.
As a side-effect this removes the debouncing. This means that user changes take effect instantly rather than after 1s.
Since there is no longer a 1s delay it is extra important that files are written safely. To this end the `thelounge add <user>` command was updated to write the user file atomically. (The update path already did this.)
Client and ClientManager deal with both 'dehydrated' channels/networks (ie. directly
from JSON configuration) and the 'rehydrated' ones (classes, with socket objects,
message arrays, etc.).
However, because their attributes are similar, both types were used interchangeably,
which becomes an issue when splitting Client's configuration loading into smaller
methods.
