Exported functions and types prefixed with apt_
  Callback added for getsample, instead of calling named function.
  Allow library to be built without libpng or libsndfile.
Add support for building with MSVC on Windows.
Fix a few MSVC compiler warnings.
Fix nonlinear radiance correction for NOAA19.

Add linear equalise
Add image flip for southbound passes
Completly remove old falseclor in favour of a much simplier method

Add the ability to open a map overlay generated by wxmap (still unstable)
Remove the ability to turn off calibration
Add MCIR images
From now on large changes to neaten up the codebase will be taking place

Improved commenting in dsp.c
Updated copyright notices
Code tidy up in some parts

This fixes the build.  It looks like the tree was forked during
some incomplete work :(

new dsp code
ngvi test

-Cleaning pll

-new resample filter
-accept different sampling rates