Add a bulk delete button

I needed this in my day job, but think we need to do better on bulk
operations

core/ui/AdvancedSearch/FilterButtons/delete.tid

@@ -0,0 +1,26 @@
+title: $:/core/ui/AdvancedSearch/Filter/FilterButtons/delete
+tags: $:/tags/AdvancedSearch/FilterButton
+
+<$reveal state="$:/temp/advancedsearch" type="nomatch" text="">
+<$button popup=<<qualify "$:/state/filterDeleteDropdown">> class="tc-btn-invisible">
+{{$:/core/images/delete-button}}
+</$button>
+</$reveal>
+
+<$reveal state=<<qualify "$:/state/filterDeleteDropdown">> type="popup" position="belowleft" animate="yes">
+<div class="tc-block-dropdown-wrapper">
+<div class="tc-block-dropdown tc-edit-type-dropdown">
+<div class="tc-dropdown-item-plain">
+<$set name="resultCount" value="""<$count filter={{$:/temp/advancedsearch}}/>""">
+Are you sure you wish to delete <<resultCount>> tiddler(s)?
+</$set>
+</div>
+<div class="tc-dropdown-item-plain">
+<$button class="tc-btn">
+<$action-deletetiddler $filter={{$:/temp/advancedsearch}}/>
+Delete these tiddlers
+</$button>
+</div>
+</div>
+</div>
+</$reveal>