navigation parameters erroneous for polar projections

[gerritholl]

For projections including a pole, the navigation parameters "meridian_east" and "meridian_west" as calculated by ninjotiff.ninjo_nav_parameters are erroneous.

I don't know if this has any implication for the NinJo client.

Example:

from pyresample import create_area_def
from pyninjotiff.ninjotiff import ninjo_nav_parameters
test_area = create_area_def(
    "test-area",
    {"proj": "stere", "lat_0": 75.0, "lon_0": 0.0, "lat_ts": 60.0,
        "ellps": "WGS84", "units": "m", "type": "crs"},
    units="m",
    shape=(1000, 1000),
    resolution=1000,
    center=(0.0, 1500000.0))
opts = {}
ninjo_nav_parameters(opts, test_area)
print(opts["meridian_east"], opts["meridian_west"])

Expected: The easternmost/westernmost meridians of this projection are 0/360 or undefined.

Actual:

36.4205936965211 -122.50013916204914

[gerritholl]

I think it's also wrong for other projections defined in metres.