view, vfilter: Add support for filtering tags and values out of a view, using !tag and field!=value.

Note that negated globs are not supported. Would have complicated the code
to add them, without changing the data type serialization in a
non-backwards-compatable way.

This commit was sponsored by Denver Gingerich.

Command/View.hs

@@ -13,8 +13,6 @@ import qualified Git
 import qualified Git.Command
 import qualified Git.Ref
 import qualified Git.Branch
-import Types.MetaData
-import Annex.MetaData
 import Types.View
 import Annex.View
 import Logs.View
@@ -46,18 +44,6 @@ perform view = do
 paramView :: String
 paramView = paramPair (paramRepeating "TAG") (paramRepeating "FIELD=VALUE")
 
-{- Parse field=value
- -
- - Note that the field may not be a legal metadata field name,
- - but it's let through anyway.
- - This is useful when matching on directory names with spaces,
- - which are not legal MetaFields.
- -}
-parseViewParam :: String -> (MetaField, String)
-parseViewParam s = case separate (== '=') s of
-	(tag, []) -> (tagMetaField, tag)
-	(field, wanted) -> (mkMetaFieldUnchecked field, wanted)
-
 mkView :: [String] -> Annex View
 mkView params = do
 	v <- View <$> viewbranch <*> pure []