[core]register_process: add a relative_to parameter to store numpy array relative to "r" values and not only "energy"

[pymca/larch] start normalization between the two process. Update display and check values for normalization vs pre_edge

For now this is just comparaison, no internal process is made to make fit the two libraries.

This require the creation of some helpers to link io and XasObject, this is the goal of xas.core.io.

[core][XasObbject] add `keep_process_flow` parameter to XasObject to automatically associate a temporary file to the XASObject process.

[core][XasObbject] add copy_process_flow_to function to copy the process flow from the current xasobject to a random hdf5 file

- now process can take an output and an output_dict for storing the result in a multiprocessing.Proxy object
- rework process action to avoid several call to pymca `processSpectrum` function
- add an option to XasObject `to_dict` function to simply store raw data (which is the reference), but also to keep processing results to be used later.
This is need for the 'non gui' workflow processing which uses a dictionnary instead of a XasObject.

[pool process + processing thread] proto - make processing in a pool and start from a separated thread to avoid gui freeze.

Move Normalization to multiprocessing.Pool and the call from orange from a dedicated thread and with a QThreadPool.
This prevent any gui freeze.
For now this is just a prototype. Some thing to do:

- create a pool_process that will be inherited from PyMca_normalization and QPyMca_normalization.
- generalize this structure for each orange widget.

Enable to display a map or the spectrum
Spectrums are only displyed with energy and mu at the moment but should evolve with time.
Maybe we would like to do the same for the map ???

This is replacing the xas_input._interpreteInput function.
The prupose of this function is to pick the default data location for creating DataUrl and calling `read_pymca_xas_from_file`

Conflicts:
	xas/core/types.py

- simplify the bases structure Spectrum and XASObject to be more generic and continue workfing with pymca.

- simplify the bases structure Spectrum and XASObject to be more generic and continue workfing with pymca.