added TaskGenerator, Task.hash(), Task reference each other via hash
moved Hash class to .hash package
split refactored out HashTask from Hash
added Hash.string()
refactored Param to use Hash.string()
added TaskTester with hashes() method
refactored FileSetTaskTest
added tests checking hashes of FileSetTask
added tests for StringSetTask hashes
added testing hashes of StringTask
added hash tests for NativeCallTask
name fixes in StringTask
inlined NodeCreator methods
name clenaup in AbstractTask
style changes in HashTest