Append pointing attitude to previous file

[subagonsouth]

Algorithm Description:

The science team has a desire to have the pointing attitude kernels cover from pointing 1 to the latest pointing. There are 2 ways to do this. The easiest change to what is currently implemented would be to:

• Update batch starter so that it provides all .ah.bc files needed to cover the time from the first pointing to the last pointing in the repoint-table that triggers the job.
• Recompute the quaternions for every pointing each time.
• Output the new file with full coverage.

The "better" way to implement this would be to "append" the new pointing data onto the end of the previous pointing attitude file and write it out as a new file. The details of the changes needed for that approach are not included in this ticket.