pio reader fixes and changes
Fixed a bug where sometimes a variable was determined to be a string when it was actually numerical data.
Modified parsing of the .pio file. Comments can now be delimited with '!' as well as '#'. Comments can be placed in the middle of a line, and possibly on the same line as a command. Spaces are allowed at the beginning of a line, as well as multiple spaces are allowed between arguments.
Changed error messages to be clearer about what is wrong.
The same changes for the paraview/release branch is this MR: !7655 (merged).
Edited by Boonthanome Nouanesengsy