started converting to use optparse-applicative

This is a work in progress. It compiles and is able to do basic command
dispatch, including git autocorrection, while using optparse-applicative
for the core commandline parsing.

* Many commands are temporarily disabled before conversion.
* Options are not wired in yet.
* cmdnorepo actions don't work yet.

Also, removed the [Command] list, which was only used in one place.

Command/FromKey.hs

@@ -19,10 +19,10 @@ import qualified Backend.URL
 
 import Network.URI
 
-cmd :: [Command]
-cmd = [notDirect $ notBareRepo $
+cmd :: Command
+cmd = notDirect $ notBareRepo $
 	command "fromkey" (paramPair paramKey paramPath) seek
-		SectionPlumbing "adds a file using a specific key"]
+		SectionPlumbing "adds a file using a specific key"
 
 seek :: CommandSeek
 seek ps = do