Add coverage task to fabfile; add coverage artifacts to .gitignore.
Add tests for next_down.
Test a handful of characteristic values for untested functions.
Exercise the trig and hyperbolic trig functions and their inverses.  Exercise log1p, expm1.
Create HTML coverage report as part of 'fab coverage'
Remove Python 2.5 compatibility code for sys.float_info.
More test coverage improvements.
Fix root function; add tests.  Fixes #60.
Exercise a few more special functions.
More coverage: tests for ai, agm, fma, fms, hypot, floor, ceil, ...
Fix comparison test on 2.x.
Update changelog.
For root function, catch negative k in bigfloat rather than mpfr.
Merge pull request #62 from mdickinson/coverage

Improve test coverage.
Merge remote-tracking branch 'origin/master' into feature/asprintf
Add docs for formatting.