relax SVN archive

Created the common API method _set_param_values_spin().

A number of modules are now using this method.

Added the api_common module to the __all__ list.

Created a module for storing API methods common to different analysis types.

Added 'HH' and 'HZ' to the amino acid atom names in __det_pdb_element().

This is in response to Tiago Pais's <tpais att itqb dot unl dot pt> post at
https://mail.gna.org/public/relax-users/2009-11/msg00002.html (Message-id:
<AF0E494FAE984C0BB8D4C8CE521D621D@...>).

Fix for the call to set_param_values().

Fixed a typo in the new generic_fns.value.set() function.

Deletion of the set_non_spin_params() method.

This mess is no longer in the base API.

Massive simplification of the generic_fns.value.set() function.

This code was previously a mess, spread randomly across the generic code and specific code. This is
a complete refactorization which will cause breakages for a little while.

Added the set_param_values() method to the base API (matching the changes of r9986).

Redesigned the specific analysis API for setting parameter values.

Now the set_param_values() method is to be provided. It is for setting single parameter values.
This will be followed by a complete redesign of the value.set() user function back end (which is
currently a mess).