Improve Flash-storage lifespan and performace

[julian-villing]

Flash-storage has a limited amount of write-cycles until it's dead

SharedPreferenceHelper.java:

• DO cache the results
• DO load/store the values once
• DO keep the values in memory
• DO NOT write every single bit instantly to disk (even if there are no changed at all)
• DO NOT access the storage repetively for every access

Sample

public class SharedPreferencesHelper
{
    private static Boolean initialized;
    private static Boolean changed;

    private static Boolean _prop1:
    private static Int32 _prop2;
    private static TYPE _NAME;

    public void Load(@OnlyIfRequired Context ctxt) { if(initialized) return; [...]; initialized = true; }

    public void Save(@OnlyIfRequired Context ctxt) { if(!changed) return; [...]; }

    public static Boolean prop1() { return prop1; }
    public static void prop1(Boolean value) {if (prop1 == value) return; prop1 = value; propertyChanged();

    [...]

    private static void propertyChanged() { changed = true; }
}

the OnlyIfRequired-Annotation should be taken literally