Refactoring of the 'hflow' script.
Added example 'comet' workflow.
Workflow instance working dir now converted to absolute path.
Removed functions (now searched automatically). HFLOW_ROOT corrected to
HFLOW_PATH.
Minor corrections in data format.
Corrected parsing of XML data.
Removed the "functions" section from the workflow description. Now it is
optional, functions are searched automatically.
Added 'appConfig' - workflow instance-specific configuration.
Implemented automatic search for file implementing workflow functions.