Improve the startup sequence.

- new welcome dialog message.
- new check units text.
- for US and UK, default to imperial.
- for fragments, fix handling of onCancel. No need
  to handle onCancel at the dialog level.

MyTracks/res/values/styles.xml

@@ -52,6 +52,15 @@ limitations under the License.
     <item name="android:selectAllOnFocus">true</item>
     <item name="android:singleLine">true</item>
   </style>
+  <!-- The style for the help answer -->
+  <style name="HelpAnswer" parent="@style/TextSmall">
+    <item name="android:paddingBottom">8dp</item>
+  </style>
+  <!-- The style for help question -->
+  <style name="HelpQuestion" parent="@style/TextMedium">
+    <item name="android:paddingTop">8dp</item>
+    <item name="android:textStyle">bold</item>
+  </style>
   <!-- The style for the list empty text view -->
   <style name="ListEmptyTextView" parent="@style/TextLarge">
     <item name="android:gravity">center</item>
@@ -147,13 +156,4 @@ limitations under the License.
     <item name="android:layout_height">wrap_content</item>
     <item name="android:layout_width">wrap_content</item>
   </style>
-  <!-- The style for the welcome page answer -->
-  <style name="WelcomeAnswerTextView" parent="@style/TextSmall">
-    <item name="android:paddingBottom">8dp</item>
-  </style>
-  <!-- The style for welcome page question -->
-  <style name="WelcomeQuestionTextView" parent="@style/TextMedium">
-    <item name="android:paddingTop">8dp</item>
-    <item name="android:textStyle">bold</item>
-  </style>
 </resources>