Fixes #27114

* Add order-*-last grid class

* copy updates

* Add first class to grid framework to add negative ordering

* Add order-first explination to the docs

Fixes #23360 by restoring just the offset class generation to our grid
framework mixins. Also restores the `make-col-offset` mixin.

Docs have been restored to illustrate this behavior and merged with the
newer margin utilities examples.

Responsive automatic column resets weren't working because they inherited their `max-width` from lower grid tiers. This was because we were resetting the `width`, not the `max-width`.

- add .col-*-auto to the extend in our grid framework mixins so it gets padding
- this means we can avoid the col-12 classes in our docs for the responsive variants

* remove the $enable-flex variable option

* remove bootstrap-flex.css dist file and it's grunt task

* remove the separate flex css file for docs; it's all the same now

* remove flexbox docs (porting some to the main grid docs in next commit)

* clean up few grid docs bits to simplify copy, start to mention flexbox

* port relevant flexbox-grid.md content to grid.md

- clean up mixins
- update how it works section
- bring over sizing and alignment sections

* remove the $enable-flex from the options.md page

* update lead paragraph to mention flexbox

* update migration to mention loss of ie9 support

* remove mention of flexbox dist file

* clarify IE support

* making a note

* remove flexbox variant mentions from component docs

- updates docs for media object, navs, list group, and cards to consolidate docs
- no more need to callout flexbox variants since it's now the default

* remove $enable-flex if/else from sass files

* remove flex dist files

* update scss lint property order to account for flex properties

* linting

* change to numberless classes for autosizing, wrap in highlighting div

* bump gruntfile and postcss to ie10

* redo intro sections

* rearrange

* phew, redo hella grid docs

- rearrange all the things
- consolidate some bits

* remove reference to flexbox mode

* more border action for demo

* Make some changes to the .card's in .card-deck's to ensure footers align to the bottom

* Remove comment that duplicated some code
* Use transition mixin whenever possible
* Create a new function to reduce duplication
* Use the new `breakpoint-infix` method

* Use `breakpoint-min` instead of a counter

* Remove 'xs' from flexbox grid

The new breakpiont-limited class pattern is to omit the breakpoint size when using the lowest size eg. col-xs-12 to col-12. This commit implements this pattern to the grid system.

.col-xs-auto, .col-sm-auto, etc.

* Fixes #20775 without adding extra width and an important flag

* Since we're now getting the extend, we don't need the extra position relative

* rerrange

* getting min-height from the extend already

- Restores two-mixin approach to generating semantic grid columns (now with 'make-col-ready' and 'make-col')
- Removes need for .col-xs-12 by restoring the mass list of all grid tier classes to set position, min-height, and padding
- Adds an initial 'width: 100%' to flexbox grid column prep (later overridden by the column sizing in 'flex' shorthand or 'width') to prevent flexbox columns from collapsing in lower viewports

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fixes #19148 as follow up to #19099: ensure local mixin variable is used for  in make-grid-columns mixin

- Flexbox responsive behavior fixed with specific .col-{breakpoint} classes now added
- Dropped the make-col mixin in favor of a column-basics placeholder that we can extend across our grid infrastructure
- Updated docs to use required .col-xs-12 (as a safeguard for when folks enable flexbox mode--this isn't necessary in default grid mode)
- Update flexbox grid docs to include responsive docs, tweak some other bits too

flip things around again, no more base class, try out some new stuff to keep responsive flex grid working

Revamp grid classes to require .col base class and improve flexbox grid classes with auto layout via flex: 1

Fixes #18036

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