expose fewer internals in packages, for easier software reuse

- prometheus is now behind an interface, they aren't dependencies for the
  reusable components anymore.
- some dependencies have been inverted: instead of packages importing a main
  package to get configuration, the main package now sets configuration in
  these packages. that means fewer internals are pulled in.
- some functions now have new parameters for values that were retrieved from
  package "mox-".

mox-/config.go

@@ -37,16 +37,20 @@ import (
 
 	"github.com/mjl-/mox/autotls"
 	"github.com/mjl-/mox/config"
+	"github.com/mjl-/mox/dkim"
 	"github.com/mjl-/mox/dns"
+	"github.com/mjl-/mox/message"
 	"github.com/mjl-/mox/mlog"
 	"github.com/mjl-/mox/moxio"
-	"github.com/mjl-/mox/moxvar"
 	"github.com/mjl-/mox/mtasts"
 	"github.com/mjl-/mox/smtp"
 )
 
 var pkglog = mlog.New("mox", nil)
 
+// Pedantic enables stricter parsing.
+var Pedantic bool
+
 // Config paths are set early in program startup. They will point to files in
 // the same directory.
 var (
@@ -397,7 +401,16 @@ func SetConfig(c *Config) {
 		}
 	}
 
-	moxvar.Pedantic = c.Static.Pedantic
+	SetPedantic(c.Static.Pedantic)
+}
+
+// Set pedantic in all packages.
+func SetPedantic(p bool) {
+	dkim.Pedantic = p
+	dns.Pedantic = p
+	message.Pedantic = p
+	smtp.Pedantic = p
+	Pedantic = p
 }
 
 // ParseConfig parses the static config at path p. If checkOnly is true, no changes