Sass/rename particle functions

[nilssass]

In this PR I do two things:

1. Renaming Member Functions

In Particle we have chosen function names that are suboptimal and not intuitive to find or they contained parts in their name that do not contain any useful information. I have renamed them to make them more precise and easier to find. They are:

Old Function Name	New Function Name
momentum_rapidity_Y()	rapidity()
spatial_rapidity()	spacetime_rapidity()
spatial_rapidity_cut()	spacetime_rapidity_cut()
pt_abs()	pT_abs()
pt_cut()	pT_cut()
compute_mass_from_energy_momentum()	mass_from_energy_momentum()
compute_charge_from_pdg()	charge_from_pdg()

2. Introducing Helper Functions

In tests/test_JetAnalysis.py we were comparing two nested lists using

# Compare the two contents
assert test_jet_finding_content == generated_jet_finding_content

However, this fails on different machines because of numerical precision when comparing floats. I have introduced a new file tests/HelperFunctions.py that contains a function to compare two lists taking into account the limits of numerical precision. This function is now used

[Hendrik1704]

We should be careful with changing the name of functions in Particle.

• Have you checked that you changed all occurrences in the codebase to the new names?
• This is a step that might make some analysis scripts of users incompatible with the new upcoming version. We have to highlight this change in the CHANGELOG.
• Since we plan to jump to version 2.0.0 next time, this backward incompatibility is already reflected in the version number.

These are just some thoughts coming to my mind after seeing the comment of your PR. Haven't had time to look at the code and the new names yet.

[nilssass]

Absolutely, the Changelog needs of course to be adjusted, this I will add. Besides that I have carefully checked for all occurrences of the functions in the entire code base and made sure that all tests pass. I see the point that renaming function names will potentially break user scripts. That's why I want to clean them up all together once, especially for version 2.0, where a user might expect some bigger changes. With this PR we should be done with name changes and all names are such that they are easily findable if an user works with an IDE.

[nilssass]

@NGoetz this PR is ready for a second review

[nilssass]

@Hendrik1704 @NGoetz Once Niklas reviewed the PR, please, do not yet merge it. I am just modifying the open PR #264 as I realized how many code duplications we have in Filters.py. I am just cleaning it up and I think it will be more efficient to first merge #264 once it is ready