R&I Misc UI 3 (#2253)

* Limits-related changes; WIP

- Renamed CSS classes: `s-limit-*` > `is-limit--*`;
- Removed load of legacy _status.scss and added new _status.scss file;
- Minor re-org of limit/status constants in theme files;
- Limit colors in theme constants all updated;

* Fixes for s-selected always displaying the move cursor

- Mod s-selected;
- Reinstitute `.is-moveable` class;

* Layout-related cleanup and refinements

- LineView cleaned up;
- Selection, hover, etc. classes for c-frame cleaned up;
- Constant names normalized, theme files updated;

* Fixes for editing plot options

- Color palette now more flexible;
- Styles for color palette button refined;
- c-input--flex added for more flexible inputs;

* Various swatch-related changes

- Swatch refinements, new .c-click-swatch class;
- Added .c-click-icon--major modifier style, applied in markup;

* Local controls class application and behavior cleanup

- Remmoved .has-local-controls from selected markup;
- Refined CSS selector for better hover behavior;

* Misc UI tweaks

- click-icon--major in Notebook;
- .test mixin improved;

* Update _constants-espresso.scss

* Update _constants-maelstrom.scss

src/plugins/displayLayout/components/LayoutFrame.vue

@@ -21,7 +21,7 @@
  *****************************************************************************/
 
 <template>
-    <div class="l-layout__frame c-frame has-local-controls"
+    <div class="l-layout__frame c-frame"
          :class="{
              'no-frame': !item.hasFrame,
              'u-inspectable': inspectable,