Add NORAD as a TLE source.

[inakimalerba]

This new source allows to use a file with multiple entries as an input
to orbit_predictor.

[coveralls]

Coverage decreased (-1.8%) to 93.348% when pulling 5d410cc on inakimalerba:norad-source into dd7ff7b on satellogic:master.

[coveralls]

Coverage decreased (-0.3%) to 94.789% when pulling 789bb10 on inakimalerba:norad-source into dd7ff7b on satellogic:master.

[coveralls]

Coverage decreased (-0.3%) to 94.789% when pulling 789bb10 on inakimalerba:norad-source into dd7ff7b on satellogic:master.

[coveralls]

Coverage decreased (-0.3%) to 94.789% when pulling 789bb10 on inakimalerba:norad-source into dd7ff7b on satellogic:master.

[coveralls]

Coverage decreased (-0.3%) to 94.789% when pulling 789bb10 on inakimalerba:norad-source into dd7ff7b on satellogic:master.

[coveralls]

Coverage decreased (-0.3%) to 94.789% when pulling 789bb10 on inakimalerba:norad-source into dd7ff7b on satellogic:master.

[coveralls]

Coverage increased (+0.1%) to 95.233% when pulling 27dd2f0 on inakimalerba:norad-source into dd7ff7b on satellogic:master.

[astrojuanlu]

Looks good to me!

[astrojuanlu]

I've been using this with great success in https://github.com/Juanlu001/groundtrack-plotting/ and it's been a while, so @gilgamezh with your permission I'm merging the PR :)

[luciotorre]

This MR references satellites by name instead of satellite ID, so it changes the convention that we currently have. Although it is nice to be able to search this way, it creates an inconsistency that we better avoid. Or we keep using ids, or we change everything to names, or we support both transparently here.

[astrojuanlu]

This MR references satellites by name instead of satellite ID, so it changes the convention that we currently have.

I don't think our convention is clear. The function parameter is called sate_id for all sources, since none of them override TLESource.get_predictor:

orbit-predictor/orbit_predictor/sources.py

Line 59 in 8d5e80a

def get_tle(self, sate_id, date):

But even the basic example in the README, that predates this PR, uses a name:

https://github.com/satellogic/orbit-predictor/blame/master/README.rst#L38

In [3]: source = EtcTLESource(filename="examples/iss.tle")

In [4]: predictor = source.get_predictor("ISS")

Perhaps we should clarify this point somewhere, or add new functions that permit retrieving names from IDs.