Spreadsheet view: add support for partial arrays
Spreadsheet view should show partial arrays.
When an array is missing on block, we simply leave the cell blank.
When user chooses File > Export Scene to export the data from the spreadsheet view to a CSV file, we popup an options dialog that lets user choose what to do with partial arrays. One can either discard them, or add them as an empty cell. One thing to note that when importing this file back in ParaView empty cells will just get interpreted as 0 for numeric columns.
Other related issues: