Allow multi-line CSVs and (optionally) use pandas

The current version of the python scripting nodes does not allow/break multi-line CSVs.

The curent approach is to init an empty table (dict of lists) with  line_count * [None] entries. However this leads to problems with multi-line CSVs. For example, if there is only one entry in the CSV but this entry is a multi-line string of n lines, the current approach will create a size n list, but create_data_table will only fill the first entry, leaving entries 1..n as None. 


Additionally, I changed the code to use pandas for reading csv if available.