Reorder file format lists to be the same as sndfile.h and api.html

* Reorders the list of recognized file formats and their filename
  extensions and aliases in programs/common.c's format_map[] and in
  sndfile-convert.1 so that the list is in the same order as in
  sndfile.h and api.html

* Adds more types that we know but format_map[] didn't use, namely
  AVR and WAVEX

* Add more filename extension aliases, insipred by those recognized
  by SoX, namely "sph" for NIST and "prc" for WVE.

Patch-from: Jan Stary <hans@stare.cz>