Add a checkbox in the preference to allow different background for multiple desktops

[XieJiSS]

Related code:

satellite-eyes/SatelliteEyes/TTMapManager.m

Lines 89 to 100 in 6631822

	// If the screens have changed, force an update.
	- (void)screensChanged:(NSNotification *)notification {
	[self updateMap];
	}
	- (void)spaceChanged:(NSNotification *)notification {
	[self updateMap];
	}
	- (void)receiveWakeNote:(NSNotification *)notification {
	[self restartMap];
	}

However, I'm not familiar with Obj-C, quite sad I cannot PR :-(

[XieJiSS]

To be clear, it will be a great bonus if it is possible to enable map background for only one desktop (just like pap.er behaves), thx a lot!