Allow encoding/decoding with higher precision

[MoonE]

Bit operations only work on 32 bit ints. The work around is to don't use bit operations where large numbers may occur.

Fixes #80

[tristen]

Suggested change

	output += String.fromCharCode((coordinate | 0) + 63);
	output += String.fromCharCode((coordinate || 0) + 63);

[MoonE]

This is intentionally a bitwise OR. In the String.fromCharCode() call in the loop above, the bitwise operation causes decimals to be discarded. I added the | 0 to remove decimals here too. I wasn't sure if a number with decimals would cause problems. In my test it worked also without rounding, but you never know how different browsers treat it ...