Architecture files can be created in $HOME/.phyex/fcm_arch
The PYFT_OPTS variable can be put in the architecture env file to add pyft transformations

Last part of #17

Use of DIFF in rain_ice_old testprog
Remove useless dimension in other testprogs

Another part of #17

Part of #17

Due to the switch between filepp/mnh_expand and pyft_tool.py,
old commits cannot be compiled with the tools provided by recent commits

This reverts commit 21056271.

Quentin 27/05/2023: update apply_pft to handle update of Stack

Quentin 1/08/2023: better documentation of apply_pft.sh and generelize application folder of the script