[schema2sql] properly consider skip_relations parameters.
This is the same bug as yams #286912. Also, introducing a unique function
telling if the relation should have a table or not unhide some other problems
related to computed relation, or missing skipped relations information.
\.svn
^build$
^dist$
\.pyc$
\.pyo$
\.bak$
\.old$
\~$
\#.*?\#$
\.swp$
^doc/book/en/apidoc$
\.old$
syntax: regexp
.*/data.*/database/.*\.sqlite
.*/data.*/database/.*\.config
.*/data/database/tmpdb.*
.*/data/ldapdb/.*
^doc/html/
^doc/doctrees/
^doc/book/en/devweb/js_api/
data.*/pgdb.*