Added 3 new styles for bar buttons. (#168)

* Added a new style called split for bar buttons

* Added wavy button styles.

* Added padding configuration

* Update bar padding

* Fix styling for battery style2

* Fix icon only setting for bar

* Update types and options

* Add button style to exported theme props.

* Fix top margin for menus.

scss/style/bar/systray.scss

@@ -1,7 +1,11 @@
 .systray button:not(:first-child) {
-  margin-left: 0.75rem;
+  margin-left: $bar-buttons-systray-spacing;
 }
 
 .systray-icon {
   font-size: 1.3em;
 }
+
+.style2.systray {
+  padding: $bar-buttons-padding_y $bar-buttons-padding_x;
+}