Remove some analysis that has no test and py interface

[RudolfWeeber]

Part of what was announced on the mailing list.

Those analysis routines without a Py interface that are either very specific to a project or entirely undocumented and untested.

Each one has a single commit, so partially reverting is possible.

Closes: #271 analysis diffusion_profile
Closes: #258 analyze ..._mol
Closes: #257 analyze cel_gpb
Closes: #248 analyze mol
Closes: #247 analyze lipid_orient_order
Closes: #246 analyze get_lipid_oriends
Closes: #244 analyze bilayer
Closes: #243 analyze modes2d
Closes: #264 analyze necklace

[codecov]

Codecov Report

Merging #1640 into python will increase coverage by 1.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           python    #1640      +/-   ##
==========================================
+ Coverage   47.51%   48.56%   +1.04%     
==========================================
  Files         393      391       -2     
  Lines       29252    28637     -615     
  Branches     5454     5293     -161     
==========================================
+ Hits        13900    13908       +8     
+ Misses      15328    14705     -623     
  Partials       24       24

Impacted Files	Coverage Δ
src/core/statistics.cpp	30.16% <ø> (+4.6%)	⬆️
src/core/virtual_sites_com.cpp	4.47% <ø> (+2.03%)	⬆️
src/core/statistics_cluster.cpp	0% <ø> (ø)	⬆️
src/core/statistics.hpp	87.5% <ø> (ø)	⬆️
src/core/p3m.cpp	83.18% <0%> (+0.78%)	⬆️
src/core/topology.hpp	100% <0%> (+50%)	⬆️
src/core/virtual_sites.hpp	100% <0%> (+50%)	⬆️

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