rework template rendering, cache parsed templates

adapt error wrapping principle

repositories/request.go

@@ -11,8 +11,8 @@ import (
 	"math/big"
 	"net/smtp"
 	"officeHours/config"
-	"officeHours/controllers"
 	"officeHours/models"
+	"officeHours/templating"
 )
 
 type RequestRepo struct {
@@ -131,12 +131,13 @@ func (r *RequestRepo) sendConfirmationMail(request models.Request) error {
 		Config  config.Config
 		Request models.Request
 	}{r.config, request}
-	err := controllers.RawTemplates.ExecuteTemplate(&message, "confirmationMail", data)
+	err := templating.WriteTemplate(&message, "confirmationMail", data)
 	if err != nil {
 		err = fmt.Errorf("Error parsing confirmation Mail: %w", err)
 		log.Println(err.Error())
 		return err
 	}
+
 	switch r.config.Mailer.Type {
 	case "Stdout":
 		fmt.Println(message.String())