ensure HTML canvas size is within browser limits

[trautmane]

Earlier today @StephanPreibisch tried to look at tile pair matches using renderScale=1.0 for two large (9417 x 8042) FIB-SEM tiles. The tiles did not render in Chrome or Firefox because (I think) the browser max area for HTML canvas elements was exceeded. This stack overflow post discusses the issue. The tile pair match UI (and all other canvas based UIs) should include size checks to prevent this type of error.