Create base class for low-level methods in parser_setup.py
Reorganize for parser model to inherit from pyramds base class

The PyramdsBase class in parser_setup.py will eventually contain only
low-level setup methods and attributes from creating setting up the
parsing framework. PyramdsParser will inherit from this class, but
contain the bulk of the actual parsing.
Create start_parse method; migrate large chunk of parsing routine over

The is the first refactor involving the migration of the bulk of the
parsing routine in the legacy code.
Add detector system variables from previous config file
Create empty SpectrumExporter class

This class inherits from PyramdsParser and will finish the workflow
from parsing to final exporting of spectra.