Rotated axis titles

[objorke]

Add a "TitleAngle" for the axes. ("Angle" is used for the tick labels)

[objorke]

Is #22 a better solution? I think the rotated titles is only needed for vertical axes.

[LukaBedi]

Hi Objorke, I really love your work and oxyplot is amazing :) i have recently come across the need to rotate the Y-axis label 90° and so i was wondering if issue #34 is solved ?

[objorke]

No, this issue is open. The question is if it should be implemented as described in #22.