TSL2561 luminosity sensor

Of course there needs to be a delineation between public constants needed for configuration (eg. tsl.C.address.FLOAT) and private constants used internally.

Alternatively, to use a better way of configuring than using a bunch of pseudo-enums.

BTW, one thing I did notice (but didn't have time to investigate last night) was the problem of chaining calls, eg.

obj
    .init(foo, bar)
    .setFoo(1)
    .getValue(function (val) {...});

rather than individual statements. The interpreter (or IDE... can't remember which) seemed to bork on the syntax.