Version 1.0.0 (native implementation)

ADDED

- Correct Pepper release paper Inspire TexKey as used in the
  `pepper_citations.tex` file written out after a run
- Summary of the most important switches after the configuration
- New logo
- Detailed build instructions and bootstrap scripts; this was in particular
  lacking before for the Kokkos variant

FIXED

- Remove accidental writeout of a `vegas.txt` file into the working directory
- Fix typos in manpage and command line help output
- Add missing colour factors in the downloaded process data

CHANGED

- Simplify process specification (#34)
    - The `process_file` setting is deprecated. It can still be used, but is
      now equivalent to the process setting. This also means that process
      files can now also be specified on the cmd line using `-p|--process`.
    - It is still possible to directly specify the process filename, e.g.
      "z2j.csv". However, it is now also possible, and preferred, to give a
      specification that follows the OpenLoops conventions. For the above
      example, this would be "ppzjj", which is then parsed and transformed
      to the correct Pepper filename before trying to read the file.
    - There is no longer a default process.
- Change default of `phasespace.optimisation.n_steps` to 7 and
  `phasespace.integration.n_nonzero_min` to 45000
- Use CMake's FetchContent method instead of git submodules to fetch external
  codes during the configuration (#36). This allows us to generate working tarballs.