[MINOR] Add support for hybrid_36 format - issue #184

[amjjbonvin]

Edited pdb_reatom, pdb_tidy and pdb_fromcif to add an option to enable the hybrid_36 format that will allow to handle/write PDB files with more than 99999 atoms.

Added tests for the news options

[rvhonorato]

This code was copied from the cctbx_project, the functions were taken directly from it - see here for example and the license conditions are not being met.

Please check the source code license agreements and make the edits here

[rvhonorato]

This PR is also adding a feature that requires a minor version number - check the CONTRIBUTING.md

[amjjbonvin]

This PR is also adding a feature that requires a minor version number - check the CONTRIBUTING.md

Which is in the name the pull request as indicated. That should trigger the minor version updated if I am correct.
And the CONTRIBUTING.md doc is wrong in stating that FEATURE should be added as this triggers a CI error.