Updates to ConstantRangeValue.__setitem__

Modifies __setitem__ to deal with a broader array of possible value 'types', such as multi-dim arrays or nested lists/tuples.

Addresses an issue with the way the values are set with the PRESF instrument
Adds module_dependencies; moves things to Abstract

Adds get_module_dependencies function to AbstractParameterType and ParameterFunctionType and exposes the function in ParameterContext and AbstractCoverage (as a @property).

Reworks function_map structure slightly and fixes get_independent_parameters and get_dependent_parameters

Moves numerous common functions into AbstractParameterType
Merge pull request #44 from blazetopher/func_mod_deps

Adds module_dependencies; moves things to Abstract
Adds _append_external_links.

Adds function _append_external_links in order to append the HDF5 external links to the master metadata file.

Initialization of a SimplexCoverage with an empty ParameterDictionary not yet handled properly due to 1-D assumption upon initialization.
Removes improper implementation of init_master.
Adds test coverage for append_parameter.