Implement new layout dir structure.

layouts/partials/menu.html

@@ -1,8 +0,0 @@
-<nav class="main-menu{{ if not ($.Param "menuinheader") }} mx--xs layout__navigation{{ end }}" aria-label="{{ i18n "menu_title" }}">
-<ul class="flex-inline mx--0">
-{{ $currentPage := . -}}
-{{ range site.Menus.main -}}
-<li><a href="{{ .URL | relLangURL }}"{{ if or ($currentPage.IsMenuCurrent "main" .) ($currentPage.HasMenuCurrent "main" .) }} aria-current="page"{{ end }}>{{ .Pre }}<span>{{ or (i18n .Identifier) .Name | safeHTML }}</span>{{ .Post }}</a></li>
-{{ end -}}
-</ul>
-</nav>