Adds `except T as ident` handling in semtempl.
Adds `except T as ident` handling in semtempl.

tulayang/Nim,dom96/Nim,russpowers/Nim,dom96/Nim,dom96/Nim,russpowers/Nim,dom96/Nim,russpowers/Nim,tulayang/Nim,russpowers/Nim,dom96/Nim,russpowers/Nim,tulayang/Nim,dom96/Nim,russpowers/Nim,tulayang/Nim,tulayang/Nim,dom96/Nim,tulayang/Nim,russpowers/Nim