Overhaul BMP085.js

Good lord! The minifier wasn't optimizing out the constants - so all those lovely verbose register names were being sent to the Espruino and *stored in memory*... 

Also removed comment inside function and a few very strange things that I suspect were optimized out by the arduino compiler for the module that this was adapted from. Stuff like Math.pow() on two constants...

Now the unminified version takes up 369 memory units, vs 413 for the *minified* old version.