Add MaterialComboBox Tagging support demo showcase and codeblocks.

Author: kevzlou7979

src/main/java/gwt/material/design/demo/client/application/addins/combobox/ComboBoxView.java

@@ -47,7 +47,7 @@ interface Binder extends UiBinder<Widget, ComboBoxView> {
 
     @UiField
     MaterialComboBox<String> comboTimeZone, comboTimeZone1, comboTimeZone2, comboTimeZone3, comboTimeZone4,
-                             comboTimeZone6, comboTimeZone7;
+                             comboTimeZone6, comboTimeZone7, comboTags, comboTagsMultiple;
 
     @UiField
     MaterialComboBox<State> comboTimeZone8, comboTimeZone8_1, comboTimeZone9, comboTimeZone9_1, comboTimeZone10,
@@ -90,6 +90,8 @@ protected void populateTimeZones() {
         addStateItems(comboTimeZone17);
         addStateItems(comboValue);
         addItemsWithoutGroup(comboCloseOnSelect);
+        addStringItems(comboTags);
+        addStringItems(comboTagsMultiple);
 
         comboTimeZone8.addValueChangeHandler(valueChangeEvent -> {
             MaterialToast.fireToast("Event: ValueChange State : " + comboTimeZone8.getSingleValue().getName() + " Value: " + comboTimeZone8.getSingleValue().getValue());

src/main/java/gwt/material/design/demo/client/application/addins/combobox/ComboBoxView.ui.xml

@@ -225,6 +225,20 @@
             </m:MaterialColumn>
         </m:MaterialRow>
 
+        <m:MaterialRow addStyleNames="code">
+            <m:MaterialBadge text="FEATURE UPDATE" textColor="AMBER" shadow="1" layoutPosition="RELATIVE" float="RIGHT" backgroundColor="AMBER_LIGHTEN_5" />
+            <m:MaterialColumn grid="l6 m6 s12">
+                <m:MaterialTitle title="Tag Support" description="Note that when tagging is enabled the user can select from pre-existing options or create a new tag by picking the first choice, which is what the user has typed into the search box so far."/>
+                <combobox:MaterialComboBox closeOnSelect="true" tags="true" placeholder="Time Zone" multiple="true" ui:field="comboTagsMultiple" />
+                <combobox:MaterialComboBox closeOnSelect="true" tags="true" placeholder="Time Zone" ui:field="comboTags" />
+            </m:MaterialColumn>
+            <m:MaterialColumn grid="s12">
+                <demo:PrettyPre addStyleNames="lang-xml">
+                    &emsp;&lt;combobox:MaterialComboBox tags="true" closeOnSelect="false" multiple="true" placeholder="Time Zone" />
+                </demo:PrettyPre>
+            </m:MaterialColumn>
+        </m:MaterialRow>
+
         <m:MaterialRow addStyleNames="code">
             <m:MaterialColumn grid="l6 m6 s12">
                 <m:MaterialTitle title="Close On Select" description="Allow or Prevent the dropdown from closing when a result is selected (Default : true)"/>