Cleanup towards release of all packages

[szabo137]

Before finalizing the releases of QEDprocesses.jl, QEDfields.jl and QEDevents.jl, the following task needs to be done in order:

• [x] finalize the pending PRs in QEDbase.jl (https://github.com/QEDjl-project/QEDbase.jl/pull/88, https://github.com/QEDjl-project/QEDbase.jl/pull/90, https://github.com/QEDjl-project/QEDbase.jl/pull/95)
• [x] release QEDbase.jl version 0.2.2
• [x] finalize the pending PRs in QEDcore.jl (https://github.com/QEDjl-project/QEDcore.jl/pull/33, https://github.com/QEDjl-project/QEDcore.jl/pull/34) which involves some updates downstream
• [ ] release QEDcore.jl version 0.1.0
• [ ] remove add_QEDcore_dev.jl from QEDprocesses.jl
• [ ] release QEDprocesses.jl version 0.2.0
• [ ] remove add_QED_dev.jl from QEDevents.jl
• [ ] release QEDevents.jl version 0.1.0
• [ ] remove add_QEDcore_dev.jl from QEDfields.jl
• [ ] release QEDfields.jl version 0.1.0

Finally, we can add all packages to QED.jl and reexport their symbols

• [ ] add QEDbase.jl to QED.jl and reexport all symbols
• [ ] add QEDcore.jl to QED.jl and reexport all symbols
• [ ] add QEDprocesses.jl to QED.jl and reexport all symbols
• [ ] add QEDevents.jl to QED.jl and reexport all symbols
• [ ] add QEDfields.jl to QED.jl and reexport all symbols
• [ ] release QED.jl version 0.1.0

Note: Here release means following the release pipeline, e.g. given here: https://github.com/QEDjl-project/QEDbase.jl/issues/78