This class implements a Base64 Character decoder as specified in RFC1113.
Unlike some other encoding schemes there is nothing in this encoding that
tells the decoder where a buffer starts or stops, so to use it you will need
to isolate your encoded data into a single chunk and then feed them
this decoder.
This class manages a cache of soft references to objects that may
take some time to load or create, such as images loaded from the
network.
Adding an object is two fold:
+ First you add the key, this lets the cache know that someone is
working on that key.