Move text interior lines variables to vtkTextProperty
When text is displayed in rows and columns (see image below), interior lines can be drawn between the different cells using the following variables:
InteriorLinesVisibility
InteriorLinesWidth
InteriorLinesColor
These were previously defined in vtkMatplotlibMathTextUtilities
which is shared between all text sources.
As a result, changing one of those variables on one text source would mistakenly apply the new value to all other text sources.