This pull-request fixes the tick-labels not being displayed part of Issue #3185

I found that the bug in due to a floating point rounding error, which is not being taken into account in the QRectF.contains method. But the equality operator does take floating point rounding into account.

Demonstration of floating point rounding errer and work-around using intersected and ==

In [41]: QtCore.QRectF(0, -5, 600, 19.77).contains(QtCore.QRectF(300, 2, 30, 12.77))
Out[41]: True
In [42]: QtCore.QRectF(0, -5, 600, 19.775).contains(QtCore.QRectF(300, 2, 30, 12.775))
Out[42]: False
In [46]: QtCore.QRectF(0, -5, 600, 19.775) & QtCore.QRectF(300, 2, 30, 12.775) == QtCore.QRectF(300, 2, 30, 12 .775)
Out[46]: True