General code enhancements

[rogerfraser]

The following enhancements are needed:

• Move DNA (.stn and .msr) file related code in dnainterop.hpp/cpp to dnaiodna.hpp/cpp
• Create a thread to display progress of interpolation from grid file.
• Create a thread to display progress of transformations.
• Consider splitting up large source code files into smaller files (of
  common functionality):
  • dnaadjust.cpp is > 14,000 lines of code
  • dnainterop.cpp is > 6,600 lines of code