Extend spacers and sizes

[unrevised6419]

Extend $spacers and $sizes like $theme-colors and other maps.

Used // stylelint-disable because stylelint complains about map on single line.

ps: Can $grid-breakpoints and $container-max-widths also be extended like this?

[mdo]

I suppose all our Sass maps should behave the same way—it'd make documentation easier. The only problem is removing values from the maps this way—you have to use map-remove. Not the end of the world, but worth noting here.

[XhmikosR]

Can't we be more explicit with what we disable here?

[unrevised6419]

As in case for other empty maps. Stylelint does not allow empty maps ex:

// stylelint-disable
$grays: () !default;
// ...
$colors: () !default;
// ...
$theme-colors: () !default;
// ...
// stylelint-enable

https://github.com/twbs/bootstrap/blob/v4-dev/scss/_variables.scss#L11

Should I add a comment line in code why I disable it?

[XhmikosR]

No worries, I remembered I had to do the same there when we switched to stylelint.

[karengrigoryan]

To add/modify values in $grid-breakpoints and $container-max-widths we still need to copy the whole map to custom.scss in 4.0.0. Any chance to extend them like other maps?

[unrevised6419]

UPDATE: You can't do this. $grid-breakpoints and $container-max-widths should be sorted
For now you can map-merge after default vars import.

[unrevised6419]

@karengrigoryan #25392