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/notebook/res/templates/entry.html

@@ -28,7 +28,7 @@
     </div>
 
     <div class="c-ne__local-controls--hidden">
-        <button class="c-click-icon icon-trash"
+        <button class="c-click-icon c-click-icon--major icon-trash"
            title="Delete this entry"
            v-on:click="deleteEntry"></button>
     </div>