feat: add new changeSetting() function

[ghiscoding]

• it's meant to be used to change a single setting at a time, for example calendar.changeSetting('range', { min: 'today' });
• this is partially related to set() #273, I'm not sure if that is what you had in mind to close the issue.
  • also related to 3.0 Roadmap most probably
• we can also see below that the method also has intelliSense and will show the user which value is available depending on the setting name provided

NOTE

I saw your code suggestion

function changeSetting(calendar: VanillaCalendar, settings: ISettings) {
  calendar.settings = { ...calendar.settings, ...settings };
}

but that might not always be a good approach because setting properties that are objects (like IRange, ISelected, ...) will be shallow merged. For example if you have 2 calendar instances and you make a change with the function you suggested, then that will change the setting on both instances

const options1 = { input: true };
const options2 = { input: true };
const calendar1 = new VanillaCalendar('#calendar-div1', options1);
const calendar2 = new VanillaCalendar('#calendar-div2', options2);
calendar1.changeSetting('range', { min: 'today' });

// with shallow copy, options1 will equal options2

... so a deep merge is better and also note that the deep merge is also extending any object properties, I gave an example in the docs :)

[ghiscoding]

This PR is actually just a suggestion and I don't necessarily need it myself, though I think it is good to have. It also supports VSCode intelliSense as shown above. I did see this request came up in #273 and also in your Roadmap 3.0, so I figured I could create this PR. If you have something in mind then feel free to modify it the way you want. Cheers

[uvarov-frontend]

As far as I can see from the code, this method allows you to change only the settings section, I will add the code so that this allows you to change any options in the calendar.

[ghiscoding]

I went this way because I thought that only settings can be changed on the calendar instance? The other options are only usable when creating the object, isn't it?

[uvarov-frontend]

In addition to the «settings», it should be possible to change the «pop-ups» and basic calendar settings.

[uvarov-frontend]

Will be added in v3.0.0 #293