Minor fixes to timers and error messages
- Fix setInterval() behavior with string times
- Incorporate test from PR #65
- Fix issue #59: context object required 'process'
- fixed a case where runAll was called and there are no timers (#70)
- Correct the clear{Interval|Timeout|Immediate} error message when calling
set*
for a different type of timer. - Lots of minor changes to tooling and the build process