Syringe: rm atypical variant spelling of "gases"
Syringe: move syringe over to make room for arrows

[#67345980]

As a side effect, moves syringe model out of "converted" folder.
Syringe: Show pulling/pushing with arrows.

[#67345980]
Syringe: work around some Lab performance issues

[#67345980]

property changes made during callEvery trigger repaints, even though the repaint should really be skipped (like in a batch operation) because callEvery callbacks only happen in situations when the model is about to be repainted anyway.