[ms] more planning bug fixes * fix sourcesterms w/ constant: all occurences of the same constant should be there once one of them is * fix handling of constant and relation in expand_terms: * we should always consider system source there for constants * for relation, we should check its lhs and rhs are in selected terms, not that the relation is in linkedterms (this has no chance to be true) This fixes 3 tests that were either passing erroneously (syt should be punished for copy/paste output as test reulst without triple checking it) or were not optimal.

oops, missing part of 6125:628cf5213154 (mapping file checking)

[ms] fix two planner bugs: one occuring query such as X created_by U where X in a external source and U may come from an ldap source. The other being that when we've to merge input maps, we were modifying the same tree/solutions while a copy were needed. Also, ensure we add type restrictions, necessary for pyro source

cleanups

[ms, c-c] new command checking for consistency / potentian flaws and enhancements of mapping file of a multi-sources instance

[repository] enabled sources refactoring: to avoid error, we should always have all known source in repo.sources_by_uri and only enabled ones in repo.sources, so we still have access to the definition of temporarily disabled sources

[migration] enhance RqlForIterator so we can do 'for e in rqliter(...).entities()'