Clean up SendDialog.java

mytracks_send_to_google.xml
- remove unused ids.
- rename id variables.
- set textSize to 18dip to fit "Google Fusion Tables".
- set margin in ScrollView because its height is 0dip
  and settings margins in its children have no effect.

SendDialog.java
- use ApiFeature.applyPreferenceChanges to commit preference changes.
- set myMapsGroup View to GONE when 'Google My Maps' is not checked.
- use Context.MODE_PRIVATE.
- onStop, call super.onStop first.

SignalStrengthSampler/proguard.cfg

@@ -0,0 +1,34 @@
+-optimizationpasses 5
+-dontusemixedcaseclassnames
+-dontskipnonpubliclibraryclasses
+-dontpreverify
+-verbose
+-optimizations !code/simplification/arithmetic,!field/*,!class/merging/*
+
+-keep public class * extends android.app.Activity
+-keep public class * extends android.app.Application
+-keep public class * extends android.app.Service
+-keep public class * extends android.content.BroadcastReceiver
+-keep public class * extends android.content.ContentProvider
+-keep public class com.android.vending.licensing.ILicensingService
+
+-keepclasseswithmembernames class * {
+    native <methods>;
+}
+
+-keepclasseswithmembernames class * {
+    public <init>(android.content.Context, android.util.AttributeSet);
+}
+
+-keepclasseswithmembernames class * {
+    public <init>(android.content.Context, android.util.AttributeSet, int);
+}
+
+-keepclassmembers enum * {
+    public static **[] values();
+    public static ** valueOf(java.lang.String);
+}
+
+-keep class * implements android.os.Parcelable {
+  public static final android.os.Parcelable$Creator *;
+}