renamed some of the variables in stdtrap.py for clarity
stdtrap.py refactoring: eliminate spurious use of r_fh
stdtrap.py: additional refactoring
stdtrap.py: refactored splicer to use sinks
stdtrap: add files=[] support to UnitedStdTrap

This adds support for "tee"ing stdout/stderr output to a file
stdtrap: prevent deadlock on account of poll.poll() never returning
stdtrap: tweak tests
stdtrap: refined tee interface + documentation + tests
release notes for v0.5
Make stdtrap main() useful
stdtrap refactoring: move Splicer from sub-class to module-level class

rational:

1) consistency with other module-level classes we use
2) UnitedStdTrap shouldn't inherit StdTrap (causes warnings)
3) makes Splicer easier to use a low-level primitive