[Dbix-class] API Changes: method renaming

[Dan Kubb]

After discussing some inconsistencies in the API with Matt on IRC, I've
changed some of the method names in DBIx::Class::Table to be more
consistent.

The changes are summarized in the following table. The first column
is the class name the second is the old method name, and the new
method name is the third column:

   DBIx::Class::PK     retrieve          -> find
   DBIx::Class::Table  retrieve_from_sql -> search_literal
   DBIx::Class::Table  count_from_sql    -> count_literal

DBIx::Class::Table->retrieve_all method has been removed, in favor
of just using DBIx::Class::Table->search({}).

The DBIx::Class::CDBICompat::Retrieve class has been added to the
CDBI Compat later to account for the changes.

In the future all methods used to perform queries will follow a
simple naming convention:

   find*   -> returns a single record (a matching record)
   search* -> returns a resultset in scalar context, or $rs->all
              in list context (all matching records)

--

Dan Kubb