Multiline and multicolumn support of MatplotlibMathText
You can now render a multiline and multicolumn math text string.
A line is defined by a '\n', and a column by '|'
For example, the string str = "Cell1 | Cell2 | $\\sum_{i=0}^\\infty x_i$\n12 | $\\sum_{i=0}^\\infty x_i$ | 2345";
is converted into this image :
Also fix rendering of text when background is fully opaque (opacity = 1) : the text is now rendered on top of the background
Also include a commit that change the default vtkTextProperty::LineSpacing from 1.1 to 1.0. Baseline have been updated