add android integration & make iOS API consistent

add pubspec android plugin

update android CMakeLists

add filament android libs for linking

android/src/main/kotlin/app/polyvox/filament/FilamentInterop.kt

@@ -0,0 +1,61 @@
+package app.polyvox.filament 
+
+import com.sun.jna.Library
+import com.sun.jna.Native
+import com.sun.jna.Pointer
+import com.sun.jna.ptr.PointerByReference
+import com.sun.jna.ptr.IntByReference
+import com.sun.jna.Structure
+import com.sun.jna.NativeLibrary
+import com.sun.jna.StringArray
+import com.sun.jna.JNIEnv
+
+import android.view.Surface
+
+import android.content.res.AssetManager 
+
+import java.nio.ByteBuffer
+
+interface FilamentInterop : Library {
+
+    fun filament_viewer_new(
+            layer:Object,
+            opaqueShaderPath:String,
+            fadeShaderPath:String,
+            env:JNIEnv,
+            am:AssetManager
+    ) : Pointer;
+
+    fun load_skybox(viewer:Pointer, skyboxPath:String, iblPath:String) : Pointer;
+
+    fun load_glb(viewer:Pointer, uri:String) : Pointer;
+
+    fun load_gltf(viewer:Pointer, uri:String, relativeResourcePath:String) : Pointer;
+    
+    fun set_camera(viewer:Pointer, nodeName:String) : Pointer;
+
+    fun render(viewer:Pointer);
+
+    fun create_swap_chain(viewer:Pointer, surface:Surface, env:JNIEnv);
+
+    fun destroy_swap_chain(viewer:Pointer);
+
+    fun update_viewport_and_camera_projection(viewer:Pointer, width:Int, height:Int, scaleFactor:Float);
+
+    fun scroll(viewer:Pointer, x:Float, y:Float, z:Float);
+
+    fun grab_begin(viewer:Pointer, x:Int, y:Int, pan:Boolean)
+
+    fun grab_update(viewer:Pointer, x:Int, y:Int)
+
+    fun grab_end(viewer:Pointer)
+
+    fun apply_weights(viewer:Pointer, weights:FloatArray, size:Int);
+
+    fun get_target_names(viewer:Pointer, meshName:String, outPtr:PointerByReference, outLen:IntByReference);
+
+    fun free_pointer(ptr:Pointer, size:Int)
+
+    fun release_source_assets(viewer:Pointer)
+
+}