New work in lib folder
Filled in missing code segments.
Fixed slight typo

Also some cosmetic changes
Added tests
Squashed a lot of bugs
Rename WrappedCallback

and other bugfixes
Fixed various bugs across the code.

Everything works as expected now.
Remove old code from branch.
Moved the test from the lib folder.
ProcessPool.createNewWorker now uses nextTick

Also, fixed bug which caused new workers from being created.
Slight correction made in package.json
Version bumped.