#153 plots do not handle axis labelling and legends properly under scaling.

[High Performance Coder]

This seems to be quite trickey to get right. One thing I discovered is that performing the calculation of placement and font size in user space leads to problems, but device space also has problems when there is an implied offset. More work needs to be done to make this robust.

[High Performance Coder]

See https://sourceforge.net/p/minsky/tickets/518/