Use normal button for grid filters

since that's more portable (for oruga) than "checkbox button"

tailbone/templates/base.mako

@@ -151,7 +151,8 @@
   ${h.stylesheet_link(request.static_url('tailbone:static/css/codehilite.css') + '?ver={}'.format(tailbone.__version__))}
 
   <style type="text/css">
-    .filters .filter-fieldname {
+    .filters .filter-fieldname,
+    .filters .filter-fieldname .button {
         min-width: ${filter_fieldname_width};
         justify-content: left;
     }

tailbone/templates/grids/filter-components.mako

@@ -181,10 +181,11 @@
         <div class="level-item filter-fieldname">
 
           <b-field>
-            <b-checkbox-button v-model="filter.active" native-value="IGNORED">
-              <b-icon pack="fas" icon="check" v-show="filter.active"></b-icon>
-              <span>{{ filter.label }}</span>
-            </b-checkbox-button>
+            <b-button @click="filter.active = !filter.active"
+                      icon-pack="fas"
+                      :icon-left="filter.active ? 'check' : null">
+              {{ filter.label }}
+            </b-button>
           </b-field>
 
         </div>