(internal) Typing support

[henryiii]

Adding typing support. Using Python 2-compatible type comments.

Currently we just have the minimum + one file fully done (pidid/functions), and basic support on Particle and with some of the other functions.

MyPy has caught a variety of potential crashes related to multiplying values with None, abs(None), etc. Whenever you return None as part of your API, that means it has to be checked at every step down the line...

We also now have full, type-checked support for using any object that SupportsInt (that is, has a __int__() special method), so you can now pass Particles directly to any of these functions!

We need to rethink or replace our loops over functions - PDGID is the main suspect. There's several options: Maybe we can simply write name = _functions.name and that will work (might be a problem in Python 2). Maybe we can simply remove the duplication of functions and methods, and make sure they work as free functions too, that is, PDGID.name(x) at a replacement for PDGID(x).name ; that would only work on Python 3, however; 2 users would need to make the object to use the method. Finally, we could just duplicate this and say that this is mostly static, so having things in two places is not too bad (the computations would be in once place, just the wrappers would be duplicated).

This fixes the ZipApp (which now requires Python 3.5+, is a bit smaller, and has a simpler setup). Dropped usage of file input, which was really designed for changing files listed on the command line and didn't work with file objects. Added a somewhat internal "_name" parameter that will overwrite the recorded file name (since some file objects do not have names, like files in zip directories).

Fixes #245. Closes #237.

To be clear: This targets 0.10. External typing support (for dependent libraries) will go into a later version as what we have is a bit hacky, but it still fixed some possible bugs and helped in a speed up the code by a factor of 100, which isn't bad.

[henryiii]

I think this is the last item before release.

[eduardo-rodrigues]

A lot of great improvements! Really nice.

[eduardo-rodrigues]

I think this is the last item before release.

You did quite a lot for the new release in the end! Honestly, I would have added the typing support after the release … but now that's done :-).

[eduardo-rodrigues]

We also now have full, type-checked support for using any object that SupportsInt (that is, has a int() special method), so you can now pass Particles directly to any of these functions!

Oh, this then needs to be documented somewhere, probably in the README at least, with some example?

We need to rethink or replace our loops over functions - PDGID is the main suspect. There's several options: Maybe we can simply write name = _functions.name and that will work (might be a problem in Python 2). Maybe we can simply remove the duplication of functions and methods, and make sure they work as free functions too, that is, PDGID.name(x) at a replacement for PDGID(x).name ; that would only work on Python 3, however; 2 users would need to make the object to use the method. Finally, we could just duplicate this and say that this is mostly static, so having things in two places is not too bad (the computations would be in once place, just the wrappers would be duplicated).

I'm not sure I understand this. For sure it makes sense to have the free functions and the identical methods in PDGID.

[henryiii]

Example of what could be done eventually:

>>> from particle import PDGID
>>>
>>> pid = PDGID(211)
>>> pid
<PDGID: 211>
>>> pid.is_meson
True
>>> pid = PDGID(99999999)
>>> pid
<PDGID: 99999999 (is_valid==False)>

For convenience, all properties of the PDGID class work as standalone functions in Python 3:

>>> PDGID.is_meson(211)
True