This commit also uses a temporary fork of boolexpr.
It allows to parse certain terms like "Niki" without choking.

Unique index is necessary when one wants to refresh the view
concurrently.

This doesn't block the whole view for the (long) period of refreshing
it.

This is safer than type Limit = Int

This big commit improves the jobs API in a way that now we can
completely abstract away over a JobLog.