Made some inner classes static (For Efficiency)

(and made one explicitly private)

Closes #3932
// FREEBIE

src/org/thoughtcrime/securesms/components/ThumbnailView.java

@@ -312,7 +312,7 @@ public class ThumbnailView extends FrameLayout {
     void onClick(View v, Slide slide);
   }
 
-  private class ThumbnailClickDispatcher implements View.OnClickListener {
+  private static class ThumbnailClickDispatcher implements View.OnClickListener {
     private ThumbnailClickListener listener;
     private Slide                  slide;
 

src/org/thoughtcrime/securesms/components/camera/CameraView.java

@@ -441,7 +441,7 @@ public class CameraView extends FrameLayout {
     ApplicationContext.getInstance(getContext()).getJobManager().add(job);
   }
 
-  private abstract class SerializedAsyncTask<Result> extends Job {
+  private static abstract class SerializedAsyncTask<Result> extends Job {
 
     public SerializedAsyncTask() {
       super(JobParameters.newBuilder().withGroupId(CameraView.class.getSimpleName()).create());

src/org/thoughtcrime/securesms/components/emoji/EmojiProvider.java

@@ -181,7 +181,7 @@ public class EmojiProvider {
     public void setColorFilter(ColorFilter cf) { }
   }
 
-  class DrawInfo {
+  private static class DrawInfo {
     EmojiPageBitmap page;
     int             index;