removed unnecessary wigglez structures
First phase of huge modification on WiggleZ likelihood

the four sublikelihoods, wigglez_a, b, c and d are now dynamically
created. A new function has been added to the class likelihood_mpk,
called add_common_knowledge. It is a way to pass global settings to
all four redshift bins.

The way the new nuisance parameters work is not yet completely set,
and will be fixed soon.
Implemented a message display function

in the module io_mp, there is now a "message" function, that takes a
string as an argument, as well as a status flag, which can so far be
"error", "warning" or "info". It then formats the string to follow
some ascii-art to represent a warning sign. The change was repercuted
through all files were it made sense.