Enabling spectrum plotting in the frequency domain

[isaacgsmith]

Resubmitting #1666

Description

This PR

• includes a "frequency" mode in TARDISSpectrum.plot().
• adds a docstring to TARDISSpectrum.plot().
• changes the axes labels in TARDISSpectrum.plot().

Motivation and context

Currently, TARDIS cannot automatically plot spectra in the frequency domain.

How has this been tested?

• Testing pipeline.
• See image below.

Examples

The following images show the implementation of my changes:

Type of change

• Bug fix.
• New feature.
• Breaking change.
• None of the above.

Checklist

• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
    • I have not but will be including that on a future PR.
  • (optional) I have built the documentation on my fork following the instructions.
• I have assigned and requested two reviewers for this pull request.

[tardis-bot]

Before a pull request is accepted, it must meet the following criteria:

• Is the necessary information provided?
• Is this a duplicate PR?
  • If a new PR is clearly a duplicate, ask how this PR is different from the original PR?
  • If this PR is about to be merged, close the original PR with a link to this new PR that solved the issue.
• Does it pass existing tests and are new tests provided if required?
  • The test coverage should not decrease, and for new features should be close to 100%.
• Is the code tidy?
  • No unnecessary print lines or code comments.

[codecov]

Codecov Report

Merging #1695 (c4436ca) into master (cc0410e) will decrease coverage by 0.02%.
The diff coverage is n/a.

❗ Current head c4436ca differs from pull request most recent head 8e3bf20. Consider uploading reports for the commit 8e3bf20 to get more accurate results

@@            Coverage Diff             @@
##           master    #1695      +/-   ##
==========================================
- Coverage   61.29%   61.26%   -0.03%     
==========================================
  Files          63       63              
  Lines        5792     5798       +6     
==========================================
+ Hits         3550     3552       +2     
- Misses       2242     2246       +4     

Impacted Files	Coverage Δ
tardis/tardis/montecarlo/spectrum.py	65.51% <0.00%> (-3.72%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update cc0410e...8e3bf20. Read the comment docs.