Improve sector module

[netfusion]

Trigger an event on the server to signal the init is done instead of using publicVariable QGVAR(ServerInitDone);

This removes the requirements for client to wait for the variable to change. Instead they can use an event handler.

[netfusion]

Another option/improvement would be to trigger an event every time a sector is created (similar to entityCreated). Provide the created sector as an argument.
Other code could use the sector immediately instead of waiting for all sectors to be created. This could be especially useful if only specific sectors are needed for a task.

This could even be a replacement for the requested serverInitDone-event (see comment above) if all procedures working on sectors are refactored to work on a single sector instead of all at once.

Refactoring example:

[_fncDrawAllSectors, {
    !isNil QGVAR(ServerInitDone) && {GVAR(ServerInitDone)}
}, []] call CFUNC(waitUntil);

becomes

["sectorCreated", {
    params ["_sector"];
    _sector call FUNC(drawSector);
}] call CFUNC(addEventHandler);