Please read my comments named "description" BEFORE doing anything! Thanks!

Some small steps need to be completed in order to enable FFmpeg to
decode indeo5 videos:

* split the 5/3 wavelet synthesis filter out of the snow source (see
  snow.c:spatial_compose53i) and adapt it to indeo5. The indeo5
  high-pass coefficients must be upscaled by -2 in this case
  before they can be passed to that filter.

* Sometimes doxygen parameters descriptions were placed in the source
  directly. Move them to the header files.
