make width/height safer with defaults, fix error in setWidth setHeight were backwards, no longer return value on null in setters, remove plotStart plotEnd not used
make width/height safer with defaults, fix error in setWidth setHeight were backwards, no longer return value on null in setters, remove plotStart plotEnd not used

crotwell/seisplotjs-waveformplot,crotwell/seisplotjs-waveformplot