Fixed precompiler to handle calls to "load" without callback (#3)

The precompiler expected the "load" and "start" functions to receive
a callback function no matter what. This may no longer be the case.
v0.7.0

Changelog since v0.6.2:
- Synchronous use of "woodman.load" possible and encouraged (#3)
- New "maxPendingEvents" option to adjust size of memory buffer (#3)
- Bug fix: "load" did not pass the error to callback function (#14)
- Bug fix: The end of substitution string was lost (#13)
- Doc: started to rewrite intro (#7)

Changelog since v0.6:
- Synchronous use of "woodman.load" possible and encouraged (#3)
- New "maxPendingEvents" option to adjust size of memory buffer (#3)
- Bug fix: "load" did not pass the error to callback function (#14)
- Bug fix: The end of substitution string was lost (#13)
- Bug fix: Time taken reported by the precompiler was incorrect (#11)
- Bug fix: Woodman crashed when logging an undefined value (#12)
- Doc: started to rewrite intro (#7)