[Frontend] IN-PROGRESS Major restructuring of /platform/commonUI/ to add themes structure

open #95
New themes bundle files, .scss and directories;
Moved constants definitions (mainly colors) from commonUI/.../_constants
to individual themes _constants files;
tweaks to mixins files;
changed pathways to font and images in commonUI/.../_constants;

platform/commonUI/themes/snow/res/sass/_mixins.scss

@@ -0,0 +1,48 @@
+@mixin containerSubtle($bg: $colorBodyBg, $fg: $colorBodyFg, $hover: false, $contrastRatio: 20%) {
+    $hovRatio: 5%;
+    $bgBase: $bg; //pullForward($bg, $contrastRatio);
+    $fgBase: $fg; //pushBack($bg, $contrastRatio);
+
+    background-color: $bgBase;
+    @include border-radius($controlCr);
+    @include box-sizing(border-box);
+    //@include boxShdwSubtle();
+    //border: none;
+    //border-top: 1px solid lighten($gradC1, 2%);
+    display: inline-block;
+    @if $hover == true {
+        &:not(.disabled):hover {
+            background-color: $colorKey; //pullForward($bgBase, $hovRatio);
+            //color: pushBack($fgBase, $hovRatio);
+        }
+    }
+}
+
+@mixin btnSubtle($bg: $colorBodyBg, $fg: $colorBodyFg, $ic: $colorBtnIcon, $contrastRatio: 20%) {
+    // $ic: Icon color
+    @include border-radius($controlCr);
+    @include containerSubtle($bg, $fg, true, 30%);
+    color: $ic;
+    .icon {
+        color: $ic;
+    }
+/*    &:not(.disabled) {
+        &:not(.paused) {
+            &:hover {
+                .icon {
+                    color: pullForward($ic, $ltGamma);
+                }
+            }
+        }
+    }*/
+}
+
+@function pullForward($c: $colorBodyBg, $p: 20%) {
+    // For dark interfaces, lighter things come forward - opposite for light interfaces
+    @return darken($c, $p);
+}
+
+@function pushBack($c: $colorBodyBg, $p: 20%) {
+    // For dark interfaces, darker things move back - opposite for light interfaces
+    @return lighten($c, $p);
+}