vicfg: Deleting configurations now resets to the default, where before it has no effect.

Added a Default instance for TrustLevel, and was able to use that to clear
up several other parts of the code too.

This commit was sponsored by Stephan Schulz

Types/TrustLevel.hs

@@ -14,6 +14,7 @@ module Types.TrustLevel (
 ) where
 
 import qualified Data.Map as M
+import Data.Default
 
 import Types.UUID
 
@@ -22,6 +23,9 @@ import Types.UUID
 data TrustLevel = Trusted | SemiTrusted | UnTrusted | DeadTrusted
 	deriving (Eq, Enum, Ord, Bounded)
 
+instance Default TrustLevel  where
+	def = SemiTrusted
+
 type TrustMap = M.Map UUID TrustLevel
 
 readTrustLevel :: String -> Maybe TrustLevel