relax SVN archive

This was reported by Martin Ballaschk <ballaschk att fmp-berlin dott de> in the thread
http://thread.gmane.org/gmane.science.nmr.relax.user/1397/focus=1402 and by by Angelo Miguel
Figueiredo <am dott figueiredo att fct dot unl dot pt> in the unrelated bug report at
https://gna.org/bugs/?20613.

The formatting string "20.15f" has been changed to "20.15g" to allow Python to decide if the normal
decimal or exponential form of the number should be printed.