V2 alpha - initial version (#172)

Initial alpha codebase for version 2 of WireGuard Portal.
This version is considered unstable and incomplete (for example, no public REST API)! 
Use with care!


Fixes/Implements the following issues:
 - OAuth support #154, #1 
 - New Web UI with internationalisation support #98, #107, #89, #62
 - Postgres Support #49 
 - Improved Email handling #47, #119 
 - DNS Search Domain support #46 
 - Bugfixes #94, #48 

---------

Co-authored-by: Fabian Wechselberger <wechselbergerf@hotmail.com>

internal/config/mail.go

@@ -0,0 +1,30 @@
+package config
+
+type MailEncryption string
+
+const (
+	MailEncryptionNone     MailEncryption = "none"
+	MailEncryptionTLS      MailEncryption = "tls"
+	MailEncryptionStartTLS MailEncryption = "starttls"
+)
+
+type MailAuthType string
+
+const (
+	MailAuthPlain   MailAuthType = "plain"
+	MailAuthLogin   MailAuthType = "login"
+	MailAuthCramMD5 MailAuthType = "crammd5"
+)
+
+type MailConfig struct {
+	Host           string         `yaml:"host"`
+	Port           int            `yaml:"port"`
+	Encryption     MailEncryption `yaml:"encryption"`
+	CertValidation bool           `yaml:"cert_validation"`
+	Username       string         `yaml:"username"`
+	Password       string         `yaml:"password"`
+	AuthType       MailAuthType   `yaml:"auth_type"`
+
+	From     string `yaml:"from"`
+	LinkOnly bool   `yaml:"link_only"`
+}