ConfigurableExtension(PreferenceScreen) support (#163)

* initial PreferenceScreen support, works with 'NeoXXX Scans' (pt-br)

* convert EditTextPreference to json successfully

* commit what I've got

* bring back the old SharedPreferences for CustomContext, implement Toast

* put back syer's implementation

AndroidCompat/getAndroid.sh

@@ -13,7 +13,7 @@ do
   which $dep >/dev/null 2>&1 || { echo >&2 "Error: This script needs $dep installed."; abort=yes; }
 done
 
-if [ $abort = yes ]; then
+if [ "$abort" = yes ]; then
   echo "Some of the dependencies didn't exist. Aborting."
   exit 1
 fi