Logic functions now in stdlib

[Reuben Thomas <rrt@...>]

I've added poor person's logic functions to stdlib (see 
LuaStandardLibraries on the lua-users.org wiki): bnot, band, bor and bxor. 
Also, _INTEGER_BITS is set the number of bits in an integer on your system 
(53 for IEEE doubles).

bitlib is recommended for those who can use it, however, and in any case 
where performance is important.

-- 
http://www.mupsych.org/~rrt/
Fate is unmoved by hope; rather, what we hope for changes (Murasaki)