[schema] Cache RQL expressions on schema loading
Add a mapping rql string to rql statement
Deserializing schema is ~36% faster with a lot (> 4000) expressions like those
generated by cubicweb-container.
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/html/index.html
Files: /usr/share/doc/cubicweb-documentation/html/*