Implements support for vertical X axes in HeatMapSeries
Implements support for vertical X axes in HeatMapSeries

This should solve the transposition issue (#535)

shoelzer/oxyplot,olegtarasov/oxyplot,oxyplot/oxyplot,zur003/oxyplot,DotNetDoctor/oxyplot,Jonarw/oxyplot,olegtarasov/oxyplot,Isolocis/oxyplot,Jofta/oxyplot,objorke/oxyplot,NilesDavis/oxyplot,HermanEldering/oxyplot,objorke/oxyplot,objorke/oxyplot,ze-pequeno/oxyplot,Kaplas80/oxyplot,shoelzer/oxyplot,DotNetDoctor/oxyplot,Kaplas80/oxyplot,shoelzer/oxyplot,HermanEldering/oxyplot