[Paraview] question-filter

[Utkarsh Ayachit]

> The dot "." in the array name is causing problems. Because it is a Python expression, the interpreter thinks you are asking for an attribute "water" from a class or module.

FYI, ParaView uses paraview.make_name_valid()[1] function to sanitize
array names in Python. Any character not a "_" or ASCII letter or
number is simply dropped and if the name beings with a number, then a
'a' is prefixed.

[1] http://www.paraview.org/ParaView/Doc/Nightly/www/py-doc/_modules/paraview/__init__.html#make_name_valid