owl doesn't like filters that use a subfilter twice

[geofft@MIT.EDU]

To reproduce:

:vu geofft
:vu nelhage
:view -d filter user-geofft or filter user-nelhage

Or even

:view -d filter personal or filter personal

It looks like owl_filterelement_is_toodeep does very much the wrong thing, and tries to determine if a filter ever contains a subfilter twice, which it seems to think is indicative of an infinite loop. Instead, it should recursively call itself, and check the recursion depth against OWL_FILTER_MAXRECURSE,

This blocks narrowing to CCs (see git://geofft.scripts.mit.edu/barnowl wip commit e5ca501), since that filter uses the personal filter once for each CC'd user.

[nelhage@MIT.EDU]

Should be fixed in f4464544a8d8ed67998d75c5715219161f0bae5f.