Upgrade Android build to Gradle build system

The old Ant build system has been deprecated for a while and new development is focused on Gradle.
I also removed a hardcoded string that lint caught and moved the patch files to a subdirectory.
I left the JNI files in the root directory.

build/android/src/debug/AndroidManifest.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+	<uses-permission android:name="android.permission.SET_DEBUG_APP" />
+</manifest>

build/android/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+		package="net.minetest.minetest"
+		android:installLocation="auto">
+	<uses-feature android:glEsVersion="0x00010000" android:required="true"/>
+	<uses-permission android:name="android.permission.INTERNET" />
+	<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
+	<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
+	<application android:icon="@drawable/irr_icon"
+			android:label="${project}"
+			android:theme="@android:style/Theme.NoTitleBar.Fullscreen"
+			android:allowBackup="true">
+		<activity android:name=".MtNativeActivity"
+				android:label="${project}"
+				android:launchMode="singleTask"
+				android:configChanges="orientation|keyboard|keyboardHidden|navigation"
+				android:screenOrientation="sensorLandscape"
+				android:clearTaskOnLaunch="true">
+			<intent-filter>
+				<action android:name="android.intent.action.MAIN" />
+				<category android:name="android.intent.category.LAUNCHER" />
+			</intent-filter>
+			<meta-data android:name="android.app.lib_name" android:value="minetest" />
+		</activity>
+		<activity android:name=".MinetestTextEntry"
+				android:theme="@style/Theme.Transparent"
+				android:excludeFromRecents="true">
+		</activity>
+		<activity android:name=".MinetestAssetCopy"
+				android:theme="@style/Theme.Transparent"
+				android:excludeFromRecents="true">
+		</activity>
+	</application>
+</manifest>

build/android/src/main/res/layout/assetcopy.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="fill_parent"
+    android:layout_height="fill_parent"
+    android:orientation="vertical" >
+
+    <ProgressBar
+        android:id="@+id/progressBar1"
+        style="?android:attr/progressBarStyleHorizontal"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center_vertical" />
+
+    <TextView
+        android:id="@+id/textView1"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:ellipsize="middle" 
+        android:singleLine="true"
+        android:layout_gravity="center_horizontal"
+        android:text="@string/preparing_media"
+        android:textAppearance="?android:attr/textAppearanceSmall" />
+
+</LinearLayout>

build/android/src/main/res/values/strings.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+	<string name="preparing_media">Preparing media...</string>
+</resources>
+

build/android/src/main/res/values/styles.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+	<style name="Theme.Transparent" parent="android:Theme">
+		<item name="android:windowIsTranslucent">true</item>
+		<item name="android:windowBackground">@android:color/transparent</item>
+		<item name="android:windowContentOverlay">@null</item>
+		<item name="android:windowNoTitle">true</item>
+		<item name="android:windowIsFloating">true</item>
+		<item name="android:backgroundDimEnabled">false</item>
+	</style>
+</resources>