Squashed commit of the following:

commit 76ad8de8
Author: Bruce Flynn <brucef@ssec.wisc.edu>
Date:   Thu May 6 15:37:10 2021 -0500

    test, then push

commit e3a51b48
Author: Bruce Flynn <brucef@ssec.wisc.edu>
Date:   Thu May 6 15:31:48 2021 -0500

    rdrgen Fix attr comparison issues, support additional mission names

commit bb6b5e6d
Author: Bruce Flynn <brucef@ssec.wisc.edu>
Date:   Thu May 6 14:11:49 2021 -0500

    modis merging working and tested

commit 58143956
Author: Bruce Flynn <brucef@ssec.wisc.edu>
Date:   Wed May 5 13:13:23 2021 -0500

    fix bad attr

commit f3bdd86d
Author: Bruce Flynn <brucef@ssec.wisc.edu>
Date:   Wed May 5 11:21:20 2021 -0500

    add module for EOS utils

commit b18d65bb
Author: Bruce Flynn <brucef@ssec.wisc.edu>
Date:   Wed May 5 11:20:59 2021 -0500

    merge: support aqua by using seqid in pointer

SNPP time of day packet (APID 10) contains only headers with no
additional user data.

Added collect_groups

Using stamp could possibly cause issues due to UTC datetimes not being
aware of leap seconds.

Replaced the merge code with something less efficient but easier to
grok.

New stream impl that does not read the data that will be used to create
and index used in new merge code.

Reimpl stream functions as classes.

Fixes issue #1.