Rewrite of the entrypoint in Golang (#71)

- General improvements
    - Parallel download of only needed files at start
    - Prettier console output with all streams merged (openvpn, unbound, shadowsocks etc.)
    - Simplified Docker final image
    - Faster bootup
- DNS over TLS
    - Finer grain blocking at DNS level: malicious, ads and surveillance
    - Choose your DNS over TLS providers
    - Ability to use multiple DNS over TLS providers for DNS split horizon
    - Environment variables for DNS logging
    - DNS block lists needed are downloaded and built automatically at start, in parallel
- PIA
    - A random region is selected if the REGION parameter is left empty (thanks @rorph for your PR)
    - Routing and iptables adjusted so it can work as a Kubernetes pod sidecar (thanks @rorph for your PR)

internal/models/alias.go

@@ -0,0 +1,24 @@
+package models
+
+type (
+	// VPNDevice is the device name used to tunnel using Openvpn
+	VPNDevice string
+	// DNSProvider is a DNS over TLS server provider name
+	DNSProvider string
+	// DNSForwardAddress is the Unbound formatted forward address
+	DNSForwardAddress string
+	// PIAEncryption defines the level of encryption for communication with PIA servers
+	PIAEncryption string
+	// PIARegion contains the list of regions available for PIA
+	PIARegion string
+	// URL is an HTTP(s) URL address
+	URL string
+	// Filepath is a local filesytem file path
+	Filepath string
+	// TinyProxyLogLevel is the log level for TinyProxy
+	TinyProxyLogLevel string
+	// VPNProvider is the name of the VPN provider to be used
+	VPNProvider string
+	// NetworkProtocol contains the network protocol to be used to communicate with the VPN servers
+	NetworkProtocol string
+)