Cannot import variable name that includes comma using the copy-paste method

[krajcsi]

csv.Sniffer cannot detect the right separator, and data rows will not be read correctly (the first variable includes all the variables with the \t separators, since Sniffer thinks that comma is the separator).

Note that this is not a bug yet in a strict sense since we don't support comma in the variable name yet, but this will be a bug when we'll support any characters.