start of async io support. Started by creating a stacklet queue
implemented lightweight threads
implement most bit-* on integers

unsigned-bit-shift-right is missing, but the others are there.
add bit-and-not for completeness
add pos?, neg? and zero?
add aget, aset and make-array
add alength for completeness
add aslice and aconcat

i'm not really happy with adding all these, but maybe they are useful to
allow writing faster low-level code in pixie.
fix aslice with negative integer arguments
Merge branch 'master' into async-io
we can dispatch to libuv, although the timeout values seem borked
latest work
add tests for the bit operations

far too extensive, but a good demonstration of the base 2 literal
syntax...
add bit-not
add array tests
very rough wip, but run_blocking works
Merge pull request #39 from heyLu/bitops-and-arrays

Bitops and arrays
reading stdlib now happens at runtime
add ns-map to get the names & vars of a namespace

it doesn't go through the refers yet, but i'm not sure if we want that.
add when-not