rdrmf5 and variable length records

There were two cancelling bugs in rdrmf4 and rdrmf5. The code to find whether a column was variable length had an error so never returned true. However, the attempt to then read all the data for a variable length column in one go is incorrect use of cfitsio, which requires such columns to be read one row at a time. Fixed both these bugs. Note that some tools still call rdrmf4 - these should be updated.

Keywords: HEAsoft