type based git config handling

Now there's a Config type, that's extracted from the git config at startup.
Note that laziness means that individual config values are only looked up
and parsed on demand, and so we get implicit memoization for all of them.
So this is not only prettier and more type safe, it optimises several
places that didn't have explicit memoization before. As well as getting rid
of the ugly explicit memoization code.

Not yet done for annex.<remote>.* configuration settings.

Assistant/WebApp/Configurators.hs

@@ -28,10 +28,10 @@ import Assistant.XMPP.Client
 import qualified Data.Map as M
 
 {- The main configuration screen. -}
-getConfigR :: Handler RepHtml
-getConfigR = ifM (inFirstRun)
+getConfigurationR :: Handler RepHtml
+getConfigurationR = ifM (inFirstRun)
 	( getFirstRepositoryR
-	, page "Configuration" (Just Config) $ do
+	, page "Configuration" (Just Configuration) $ do
 #ifdef WITH_XMPP
 		xmppconfigured <- lift $ runAnnex False $ isJust <$> getXMPPCreds
 #else
@@ -62,7 +62,7 @@ makeCloudRepositories = $(widgetFile "configurators/repositories/cloud")
 
 {- Lists known repositories, followed by options to add more. -}
 getRepositoriesR :: Handler RepHtml
-getRepositoriesR = page "Repositories" (Just Config) $ do
+getRepositoriesR = page "Repositories" (Just Configuration) $ do
 	let repolist = repoListDisplay $ RepoSelector
 		{ onlyCloud = False
 		, onlyConfigured = False