Template.py: make filter warnings conditional and allow for no ctf_params

[sroet]

replaces #88

I got a question from a novice user that thought it was bad when he did not specify the lowpass filter.
This now makes the log message conditional to the input

During the writing of the test I saw that there was code handeling ctf_params=None (line 73), so I added that option as a default to the call as well

[McHaillet]

Thanks for the PR to address it!

I was thinking it might be better if there is no warning message if the filter is not set.
Only if its set and too low, it should give a warning that it is reseting to nyquist resolution.
Something like:

if filter_to_resolution is None:
    filter_to_resolution = 2 * output_spacing
elif filter_to_resolution < (2 * output_spacing):
    logging.warning('...')
    filter_to_resolution = 2 * output_spacing

[sroet]

Thanks for the PR to address it!

I was thinking it might be better if there is no warning message if the filter is not set. Only if its set and too low, it should give a warning that it is reseting to nyquist resolution. Something like:

if filter_to_resolution is None:
    filter_to_resolution = 2 * output_spacing
elif filter_to_resolution < (2 * output_spacing):
    logging.warning('...')
    filter_to_resolution = 2 * output_spacing

You are right, was my preferred solution as well 👍 I altered it to that, please have another look

[McHaillet]

LGTM