GitLab

- Sphinx now 4.*
- Fixed finesse_sphinx to work with Sphinx 4
- Updated sphinxcontrib-bibtex to 2.2.* to remove need for version pinning < 2.*
- Most other packages pinned to their latest PyPI versions
- Requirements files now don't pin versions for non-production tools (docs, build, etc.)

Store Cython extension sources as relative paths in setup.py

See merge request !78

1;95;0cMerge branch 'develop' of git.ligo.org:finesse/finesse3 into develop

so that the SOURCES.txt file generated by setuptools contains only relative paths - absolute paths can confuse windows

Don't open already open files in the test suite

Closes #361

See merge request !80

that doesn't work on windows

that doesn't work on windows

As discussed in the telecon

This dependency made it necessary for end users to install Cython even when using pre-built binary wheels.

The conda package will just be a wrapper around the PyPI wheels, and can't easily be tested
for each commit (yet) so removing for now.
Relevant chat: https://chat.ligo.org/ligo/pl/5t1uhntodbdapripqkntr6n6do

- add two sections to the higher order modes physics part:
    1) deriving the different formulae
    2) studying convergence and scaling
- add example 10 doing Finesse simulations to verify the formulae derived in 1)