EELS&CL for particles inside arbitrary host medium

[alkichigin]

Description

This adds the possibility for simulating electron energy loss spectroscopy and cathodoluminescence for particles embedded into infinite arbitrary host medium.

Related issues

https://github.com/adda-team/adda/issues/91 https://github.com/adda-team/adda/issues/155

Types of changes

What types of changes does your code introduce to ADDA? Put an x in the boxes that apply

• [ ] Bugfix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

Put an x in the boxes that apply. Typically, all boxes need to be checked before the final merge, but you can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. If you think that some of them are not relevant, discuss this below.

• [x] I have read the contributing guidelines
• [ ] The new code complies with the existing code style.
• [x] The code compiles correctly in all relevant regimes (at least, make seq)
• [ ] The new code does not rely on any Fortran or C++ sources or is disabled by NO_FORTRAN or NO_CPP preprocessor macros, respectively.
• [x] The change neither adds or removes files; otherwise, these changes are reflected in README.md in corresponding folders.
• [ ] No warnings appear during debug compilation (at least, make seq OPTIONS=DEBUG, but better devtools/build_debug) or they are discussed below
• [ ] Tests pass locally with my changes (at least, sh comp2exec seq in tests/2exec, but better devtools/test_new [seq]). If any errors appear, they are discussed below.
• [ ] I have added tests that prove my fix is effective or that my feature works. And these tests pass. This includes new command line in suite files in tests/2exec (and potentially new ignore patterns). In some cases, it is desirable to add new tests to tests/equiv.
• [ ] I have added/extended necessary documentation (if appropriate). If suggesting changes to the manual, I have used "Track changes" in the doc file.
• [x] I have looked through all changes introduced by this pull request (line by line), using git diff or, better, some GUI tool, to ensure that no unexpected changes are introduced.