signals and slots for all ProjectData classes (and update ui only based on recived signals and not always)

[ma7t3]

Unfortunately, it doesn't seem to be any faster than the old method, in fact it's even slower, so perhaps we'll leave it alone after all.

[ma7t3]

Unfortunately, it doesn't seem to be any faster than the old method, in fact it's even slower, so perhaps we'll leave it alone after all.