visibility: hidden !important (#1289)

* visibility: hidden !important

* CHANGELOG.md

* docs

* docs fix

sass/base/helpers.sass

@@ -185,6 +185,45 @@ $displays: 'block' 'flex' 'inline' 'inline-block' 'inline-flex'
   .is-hidden-fullhd
     display: none !important
 
+.is-invisible
+  visibility: hidden !important
+
++mobile
+  .is-invisible-mobile
+    visibility: hidden !important
+
++tablet
+  .is-invisible-tablet
+    visibility: hidden !important
+
++tablet-only
+  .is-invisible-tablet-only
+    visibility: hidden !important
+
++touch
+  .is-invisible-touch
+    visibility: hidden !important
+
++desktop
+  .is-invisible-desktop
+    visibility: hidden !important
+
++desktop-only
+  .is-invisible-desktop-only
+    visibility: hidden !important
+
++widescreen
+  .is-invisible-widescreen
+    visibility: hidden !important
+
++widescreen-only
+  .is-invisible-widescreen-only
+    visibility: hidden !important
+
++fullhd
+  .is-invisible-fullhd
+    visibility: hidden !important
+
 // Other
 
 .is-marginless