Release v0.1.2

---------------
Layout managers added.
Some bugs fixed.
Copyright added.
Arts resized.
README.md updated.
CHANGELOG.md updated.
Unused garbage removed.

gallerydroid/src/main/res/layout-v21/fragment_picture.xml

@@ -0,0 +1,22 @@
+<!--
+  ~ Copyright (c) 2021 jesusd0897.
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~ http://www.apache.org/licenses/LICENSE-2.0
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<com.github.chrisbanes.photoview.PhotoView xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/photo_view"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:adjustViewBounds="true"
+    android:scaleType="fitCenter"
+    android:transitionName="picture_view"
+    tools:src="@tools:sample/backgrounds/scenic" />