Add Logging Interface

[xiphirx]

It is useful to have very fine grained logging information, the library should provide a logging interface that users can utilize to get more in-depth information on what goes on internally.

This should probably adopt a builder-like pattern, maybe

ReLinker.log(myLogger).loadLibrary(context, "badlib");

or perhaps, just attach a logger once

ReLinker.attachLogger(myLogger);

[xiphirx]

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