[IMP] adapt all calls to ormcache() to its new API

This fixes a bug on some methods.  Because `ormcache` uses the decorator
`decorator`, the `context` argument is passed positionally to the decorated
lookup method, instead of being passed as a keyword argument.  As a
consequence, the context dictionary is included in the cache key, which makes
the cache lookup fail all the time.

Using the new API of `ormcache` gracefully fixes this issue.