Update planes.py

[GaryLZW]

Add minor change to docstrings and remove TODOs that have been resolved

[GaryLZW]

Please ignore the previous changes. Sorry, I don't know how to get rid of those. The last two commits are new.

[codecov[bot]]

Codecov Report

Merging #121 (225ec01) into master (890747f) will decrease coverage by 0.98%. The diff coverage is n/a.

:exclamation: Current head 225ec01 differs from pull request most recent head 1a42f87. Consider uploading reports for the commit 1a42f87 to get more accurate results

@@            Coverage Diff             @@
##           master     #121      +/-   ##
==========================================
- Coverage   84.82%   83.84%   -0.98%     
==========================================
  Files          68       67       -1     
  Lines        2702     2786      +84     
==========================================
+ Hits         2292     2336      +44     
- Misses        410      450      +40     

Flag	Coverage Δ
unittests	83.84% <ø> (-0.98%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
carmm/analyse/planes.py	31.25% <ø> (ø)

... and 5 files with indirect coverage changes

[GaryLZW]

Hi @JackWarren23, I made some minor change to your docstrings and comments. Could you please have a look and see if these make sense? Zhongwei