[orx-minim] Fix audio file loading, add demo (#280)

orx-jvm/orx-minim/src/demo/kotlin/DemoPlaySound01.kt

@@ -0,0 +1,24 @@
+import org.openrndr.application
+import org.openrndr.extra.minim.minim
+
+fun main() {
+    application {
+        program {
+            val minim = minim()
+            val player = minim.loadFile(
+                "demo-data/sounds/26777__junggle__btn402.mp3"
+            )
+
+            // fade gain to -40dB in 15 seconds
+            player.shiftGain(player.gain, -40f, 15000)
+
+            extend {
+                if(frameCount % 30 == 0) {
+                    player.rewind()
+                    //player.gain = Random.nextDouble(-20.0, 0.0).toFloat()
+                    player.play()
+                }
+            }
+        }
+    }
+}

orx-jvm/orx-minim/src/main/kotlin/Minim.kt

@@ -3,10 +3,11 @@ package org.openrndr.extra.minim
 import ddf.minim.Minim
 import org.openrndr.Program
 import java.io.File
+import java.io.InputStream
 
 class MinimObject {
     fun sketchPath(fileName:String) = "./"
-    fun createInput(fileName: String) = File(fileName).inputStream()
+    fun createInput(fileName: String) = File(fileName).inputStream() as InputStream
 }
 
 fun Program.minim(): Minim  {