[Frontend] Apply flex layout to object header elements

open #250
open #260
vista#132
Major refactoring to markup and CSS to apply
flex layout strategy to object headers;
Flex necessary to fix 'overflow: hidden' setting
applied in open90 to object-browse-bar that
was preventing the view switcher menu from
appearing;
Browse, edit, mobile, frames in layouts, etc. all
visually checked in a first go round;
Mobile classes tweaked to fix left and right
margin problems resulting from open90 changes;
z-indexing of Inspector pane and splitters changed
to allow primary pane elements to overflow beneath
when primary pane width is severely constrained;

platform/commonUI/edit/res/templates/topbar-edit.html

@@ -22,7 +22,8 @@
 <div class='top-bar edit abs'>
     <mct-representation key="'object-header'"
                         mct-object="domainObject"
-                        parameters="{ mode: 'Edit' }">
+                        parameters="{ mode: 'Edit' }"
+                        class="l-flex-row flex-elem grows object-header">
     </mct-representation>
     <div class='buttons-main btn-bar buttons abs'>
         <mct-representation key="'switcher'"