Make time independent tracing output by default in one file per process
Structure is filename.txt : list of all the files to open
folder filename.txt_files : all files, with unique names (so that they won't be erased by a new run, only the main one will)

Adds an option tracing/smpi/format/ti_one_file to only use one subfile and put every event in it
For larger runs this will avoid opening too many handles.
Trace buffer is not to be handled by the format-dependent init functions
change tesh test to account for new structure in time independent traces
Not ideal, as tesh is a bit too strict to allow us to really compare the files
Revert "New G5K platform file generated from the G5K API"

This reverts commit e250f9b93ba79d49b6fc6a9e4e63f4de65e334b5.

I suppose this commit is related to Laurent Pouilloux's work?
I don't think it's really ready to be committed into SimGrid:
- please add some provenance information (version of the testbed
  description, date of generation at least)
- please point to the tools used to generate the platform file
  (or commit them to git), and some documentation about how
  to re-do the process
- please use the <cluster> tag to avoid such a gigantic file
- please don't override the previous g5k.xml file, but rather keep
  it (for historical / XP reproducibility purposes). maybe name
  the new file g5k-11.2013.xml or sthing?