Move files to build directory

Move the downloaded files to build directory and moved the unzip folder to the build directory so that they are ignored by git and cleaned appropriately.

jme3-android-native/decode.gradle

@@ -14,27 +14,27 @@ String decodeSourceDir = 'src/native/jme_decode'
 
 task downloadStbImage(type: MyDownload) {
     sourceUrl = stbiUrl
-    target = file('stb_image.h')
+    target = file(decodeBuildDir + File.separator + 'stb_image.h')
 }
 
-// Copy stb_image.h to the source directory.
+// Copy stb_image.h to the jni directory.
 task copyStbiFiles(type: Copy) {
-    def sourceDir = file('stb_image.h')
+    def sourceDir = file(decodeBuildDir + File.separator + 'stb_image.h')
-    def outputDir = file(decodeSourceDir + File.separator + "STBI")
+    def outputDir = file(decodeBuildJniDir + File.separator + "STBI")
     from sourceDir
     into outputDir
 }
 copyStbiFiles.dependsOn {
-    def stbiFile = file('stb_image.h')
+    def stbiFile = file(decodeBuildDir + File.separator + 'stb_image.h')
     if (!stbiFile.exists()) {
         downloadStbImage
     }
 }
 
-// Copy libtremor source to the source directory.
+// Copy libtremor source to the jni directory.
 task copyTremorFiles(type: Copy) {
     def zipFile = file(tremorZipFile)
-    def outputDir = file(decodeSourceDir + File.separator + "Tremor")
+    def outputDir = file(decodeBuildJniDir + File.separator + "Tremor")
 
     from (zipTree(zipFile)) {
         include '*.c'