FlowCmdM -> DBCmd or HasNodeStory is usually enough

This is safer than type Limit = Int

This turned out to be quite heavy because of module import cycles.

Also, (length allDocs) queries were replaced by proper count queries
from the DB which is more efficient, except for the table query (this is
a bit more complex).

[API/DB] Fav AND Delete in NodeNode => category as Int wher 0 = Deleted, 1 or null = Neutral, 2 = Favorite.