Use std::optional for options

[mwestphal]

• Force CXX_STANDARD 17 for F3D and libf3d
• Use std::optional for options where that makes sense adapting the code along the way
• Remove many limitations caused by "default" value triggering behaviors
• Split point-size in two options, point-sprites-size and point-size
• Fix scene.animation.time is initialized to zero, which may have unexepected effect with time range not starting at zero #1354 and add a test for it
• Some options will be converted to optional in Add a meta importer #1609
• add options::isSet, options::getSetNames and add testing for it
• update doc, python bindings, tests

Issues to open:

• Unset/Reset API + Special CLI syntax to unset an option: Add an API to reset/unset options and expose it at CLI level #1623
• Improve C++17 API: Take advantage of libf3d C++17 API #1624

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.84%. Comparing base (743f4f7) to head (4b7e3f9).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1617      +/-   ##
==========================================
+ Coverage   96.82%   96.84%   +0.02%     
==========================================
  Files         108      108              
  Lines        7643     7668      +25     
==========================================
+ Hits         7400     7426      +26     
+ Misses        243      242       -1     

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[Meakk]

Other than the two comments, that looks very good!

[snoyer]

IMO the class method that return all the possible names should be static getAllNames() and the instance method that returns the names that do have a value at the time should be just getNames().

Alternatively, do we actually need the filtered names method in the API in the first place?
It looks like it is only used for the python bindings and once in the app so it would be possible to:

• inline the hasValue(name) check in the loop in F3DStarter.cxx
• use std::copy_if and std::count_if in the Pybind code

[mwestphal]

IMO the class method that return all the possible names should be static getAllNames() and the instance method that returns the names that do have a value at the time should be just getNames().

It was you suggesting to NOT use getNames() I'm fine with either.

Alternatively, do we actually need the filtered names method in the API in the first place? It looks like it is only used for the python bindings and once in the app so it would be possible to:

* inline the `hasValue(name)` check in the loop in `F3DStarter.cxx`

* use `std::copy_if` and `std::count_if` in the Pybind code

This method is needed imo.

wdyt @Meakk

[snoyer]

It was you suggesting to NOT use getNames() I'm fine with either.

Yes I suggested static getAllNames() to contrast with getSetNames() but @Meakk rightly pointed out that getSetNames() wasn't great ("get" and "set" in the same name is meh in the programming context because the terms are loaded because of getters and setters. It's just unfortunate that it's an irregular verb and the spelling of the past participle collides with that of the infinitive getSettedNamed would not have had that issue, oh well).
However I'm not sure "valued names" is immediately obvious either :/ but maybe that's just me, in which case carry on :)