Begin to supply size-safe interface by default
o Accept std::string, vectors, arrays of arbitrary numeric types,
  and map them to the underlying R-S datum and symbol sizes, with
  appropriate bit masking.
Improve interface, and add comparative testing with Phil Karn's version
o Add a generic ezpwd::reed_solomon_base base class with virtual methods
  providing size-safe access to specific Reed-Solomon implementations.
o Provide mapping and masking of data with larger bit widths onto
  R-S codecs with smaller symbols, allowing correction of errors
  over a subset of the bits in the data.
o Integrate ezpwd::array into the <rs> header file; there is now
  exactly one file required to supply the entire implementation.
Merge branch 'fix-interface'