Speedup

Regarding this:
https://sourceforge.net/p/qlcplus/discussion/general/thread/6b1d73d9/?limit=25#8de8

I've looked around and found some tweaks to improve performance, especially in this specific case: chasers built from an rgbmatrix.

I managed to go from 5 seconds to open the workspace to <1 sec, and running the 8 chasers at the same time appears fluid.

Changes made :

- Containers switching
- A different signal for functionChanged and functionNameChanged (functionChanged is sent a lot of times in this case, and the ui tries to update the function list because of this, but it is not necessary if the name of the function has not changed) : still some work to do here


I can upload gprof results here to show the benefits from each change.

Regards.