Changed Warngen Toolbar button to have yellow background

icons/warngen.gif
- copied this icon from the warngen plugin (com.raytheon.viz.warngen/icons) which is where the NWS version sets this button

plugin.xml
- created a new toolbar section for the warngen button (because otherwise all icons in the same section have the same width, so this makes the nsharp and browser icons way wider than they should be)
- moved the warngen command into this new toolbar section, and set the icon on the command and removed the label (this is because you can't simply set the background for the button, so this gives it the desired yellow background)

cave/com.raytheon.uf.viz.d2d.ui/plugin.xml

@@ -560,11 +560,10 @@
             </command>
             </toolbar>
             <toolbar
-               id="applications">
+                  id="warngenButton">
                <command
                      commandId="com.raytheon.viz.warngen.gui.WarngenAction"
-                  label="Warngen"
-                  mode="FORCE_TEXT">
+                     icon="icons/warngen.gif">
                   <visibleWhen>
                      <and>
                         <reference
@@ -578,6 +577,9 @@
                      </and>
                   </visibleWhen>
                </command>
+            </toolbar>
+         <toolbar
+               id="applications">
                	<command
                   commandId="com.raytheon.uf.viz.d2d.nsharp.dialog"
                   icon="icons/nsharp.png"