Convert android project to example project

Raylib-cs.Android/android.patch

@@ -1,27 +0,0 @@
-diff --git a/src/rcore.c b/src/rcore.c
-index eae4951..4400b22 100644
---- a/src/rcore.c
-+++ b/src/rcore.c
-@@ -1,3 +1,22 @@
-+#if defined (PLATFORM_ANDROID)
-+#include <stdlib.h>
-+
-+typedef void (*RaylibAndroidCallback)();
-+static RaylibAndroidCallback _androidCallback = NULL;
-+
-+void RaylibSetAndroidCallback(RaylibAndroidCallback callback) {
-+  _androidCallback = callback;
-+}
-+
-+int main(int argc, char *argv[]) {
-+  (void)argc;
-+  (void)argv;
-+  while (_androidCallback == NULL) {
-+  }
-+  _androidCallback();
-+}
-+#endif
-+
- /**********************************************************************************************
- *
- *   rcore - Basic functions to manage windows, OpenGL context and input on multiple platforms