Allow user to upload previous recorded tracks

app/app.iml

app/src/main/AndroidManifest.xml

app/src/main/java/uk/org/mapthepaths/android/Constants.kt

.../main/java/uk/org/mapthepaths/android/GpxFilesActivity.kt

...c/main/java/uk/org/mapthepaths/android/GpxFilesAdapter.kt

app/src/main/java/uk/org/mapthepaths/android/GpxUploader.kt

app/src/main/java/uk/org/mapthepaths/android/MainActivity.kt

app/src/main/java/uk/org/mapthepaths/android/OSMProcessor.kt

app/src/main/res/layout/gpx_files.xml

app/src/main/res/menu/menu.xml

app/src/main/res/values/strings.xml