messages: custom content described in customcontent.go, message tests

customcontent.go constains a structure with all the custom content,
methods for getting display names, subjects, etc., and a list of
variables, conditionals, and placeholder values. Tests for constructX
methods included in email_test.go, and all jfa-go tests can be run with
make INTERNAL=off test.

api-userpage.go

@@ -264,7 +264,7 @@ func (app *appContext) ModifyMyEmail(gc *gin.Context) {
 		}
 		app.debug.Printf(lm.EmailConfirmationRequired, id)
 		respond(401, "confirmEmail", gc)
-		msg, err := app.email.constructConfirmation("", name, key, app, false)
+		msg, err := app.email.constructConfirmation("", name, key, false)
 		if err != nil {
 			app.err.Printf(lm.FailedConstructConfirmationEmail, id, err)
 		} else if err := app.email.send(msg, req.Email); err != nil {
@@ -643,7 +643,7 @@ func (app *appContext) ResetMyPassword(gc *gin.Context) {
 			Username: pwr.Username,
 			Expiry:   pwr.Expiry,
 			Internal: true,
-		}, app, false,
+		}, false,
 	)
 	if err != nil {
 		app.err.Printf(lm.FailedConstructPWRMessage, pwr.Username, err)