[breadcrumb] infinite loop safety belt, bw compatible by hi-jacking 'recurs' argument

[login] fix some previously introduced login box css breakage

[components] refactor main template header: make it much more flexible by using CtxComponent * rename userlink class (not private) with somewhat bw compat * make some cosmetic adjustements on log-in/registration components * update to component api, though this may breaks some sub-classes (for application customizing the breadcrumbs component for instance)

[schema / sources] store data sources as cubicweb entities this implies several changes: * new CWSource / CWSourceHostConfig entity types * only the system sources and default admin login/password stored in sources file (other stuff will be ignored) * on startup, get sources definition from the database * every entities have a cw_source relation * a facet allow filtering

[hook/operation] nicer api to achieve same result as set_operation, as described in #1253630

backport stable

[devtools] refactor http server initialization in a much saner way Use a new ApptestConfiguration to group server paramater. Fix base-url mangling between main site and data ressources.

[pre 3.10 compat] if CtxComponent as a call() method, emit a deprecation warning but use it. Also ensure default value on class for visible and order, and define wview for bw compat as well

[reledit] do not reload on the parent node

[js/edition] kill deprecated (& dead) reledit code