implement `topocg` module and helper functions

[rversin]

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[amjjbonvin]

Should probably not be gzipped as they will be used later on in the cg-to-aa module

[rvhonorato]

This is currently at +5,566 lines and I assume you are not close to being done, please break it down into smaller PRs

[amjjbonvin]

Or - so we make subbranches of the topocg branch and merge every time into the topocg branch, which we should rename to CG-HADDOCK for example