cubicweb-card #2967198 allow / in wikiid [validation pending]

This would be useful to create a pages hierarchy, which is a typical feature of wiki.

prioritynormal
typeenhancement
done in0.5.0
load1.000
load left0.000
closed by#fec0385a0e90 Implement directory-like structure of wiki pages (closes #2967198)
patchImplement directory-like structure of wiki pages (closes #2967198) [applied]