This example tests the use of images in ph.x. It computes the phonon 
dispersions of AlAs as in example02 and the dispersions of Al as in example14.

NB: This example requires PARA_IMAGE_PREFIX and PARA_IMAGE_POSTFIX to be
set in environment_variables file. The image calculation must run with
a number of processors equal to the number of images multiplied by the number
of processors used in the pw.x run.

The calculation (run_example) proceeds as follows:

1) make a self-consistent calculation for AlAs without images
   (input=alas.scf.in, output=alas.scf.out).

2) make a phonon dispersion calculation with images. Each image calculates
   a part of the q points and of the irreducible representations.
   (input=alas.ph.in, output=alas.ph.out, out_1_0, ..., out_N_1, N is
    the number of images).

3) make a phonon dispersion calculation without images recovering the
   information from outdir/_ph0/{prefix}.phsave. This is a fast calculation
   where the dynamical matrices are collected, diagonalized, and written 
   on the working directory.
   (input=alas.ph.in1, output=alas.ph.out1).

4) The rest proceeds as in example02.


Similarly for example14. The two phonon calculations are done using
the image features and then collected.
