- [settings] better formatting for `settings.assets`
- [settings] moved `$apply-color-to-...headings` to `settings.options`; better formatting
- [settings][base][mixins] dropped support of rems, thus cutted out all `$use-rems`-related declarations
- [settings] moved `$base-bg` from `settings.colors` to `settings.assets`
- [settings] better formating for `settings.options`
- [settings] better formating for `settings.responsive`
- [settings][generic][objects] renamed `$use-...` to `$enable-...`
- [settings] renamed `$base-form-...` to `$forms-...`; better formatting for `settings.typography`
- [settings] renamed `$base-form-...` to `$forms-...` in `settings.colors`
- [generic] renamed `$base-form-...` to `$forms-...` in `forms` due to latest changes