Integrate QEDfields.jl

[szabo137]

The subpackage QEDfields.jl needs to be integrated into QED.jl. This includes the following tasks:

• make the top-level namespace of QEDfields.jl available in QED.jl
• add docs of QEDfields.jl as a page to the docs of QED.jl
• add integration tests from QEDfields.jl into the test suite of QED.jl
• pin the version of QEDfields.jl used in the current version of QED.jl

Requirements

The following items are required for QEDfields.jl to be integrated into QED.jl:

• implementation of the generic spectrum for different pulse shapes, e.g. gauss and cos-square pulse
• implementation of a simple interface to configure the calculations of generic spectrums
• implementation of conversion functions for laser parameter and theory constants, e.g. $I_L, \omega \leftrightarrow a_0, \chi$
• unit tests to check the exposed functions for correctness (this will be called by QED.jl test suite)
• integration tests for any dependency within QED.jl (this will be called by QED.jl test suite)

The docs of QEDfields.jl should at least contain

• a landing page in the QEDfields.jl docs describing the purpose of the package
• API reference for all exposed functions and data types, as well as the respective page in the docs of QEDfields.jl
• a quickstart section showing the main functionality