Escape file names in coverage table

[augustozanellato]

Underscores are not escaped in filenames so instead of __init__.py file names are rendered as init.py.
My proposed fix would be replacing coverFile.file here with coverFile.file.replaceAll("_", "\\_").
A proper solution would be to find some way to escape markdown, but this should cover the majority of use cases.

[orgoro]

v3.1

[augustozanellato]

Thanks!