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/splash/splash.go

@@ -0,0 +1,55 @@
+package splash
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/kyokomi/emoji"
+	"github.com/qdm12/private-internet-access-docker/internal/constants"
+	"github.com/qdm12/private-internet-access-docker/internal/params"
+)
+
+func Splash(paramsReader params.ParamsReader) string {
+	version := paramsReader.GetVersion()
+	vcsRef := paramsReader.GetVcsRef()
+	buildDate := paramsReader.GetBuildDate()
+	lines := title()
+	lines = append(lines, "")
+	lines = append(lines, fmt.Sprintf("Running version %s built on %s (commit %s)", version, buildDate, vcsRef))
+	lines = append(lines, "")
+	lines = append(lines, annoucement()...)
+	lines = append(lines, "")
+	lines = append(lines, links()...)
+	return strings.Join(lines, "\n")
+}
+
+func title() []string {
+	return []string{
+		"=========================================",
+		"============= PIA container =============",
+		"========== An exquisite mix of ==========",
+		"==== OpenVPN, Unbound, DNS over TLS, ====",
+		"===== Shadowsocks, Tinyproxy and Go =====",
+		"=========================================",
+		"=== Made with " + emoji.Sprint(":heart:") + " by github.com/qdm12 ====",
+		"=========================================",
+	}
+}
+
+func annoucement() []string {
+	timestamp := time.Now().UnixNano() / 1000000000
+	if timestamp < constants.AnnoucementExpiration {
+		return []string{emoji.Sprint(":rotating_light: ") + constants.Annoucement}
+	}
+	return nil
+}
+
+func links() []string {
+	return []string{
+		emoji.Sprint(":wrench: ") + "Need help? " + constants.IssueLink,
+		emoji.Sprint(":computer: ") + "Email? quentin.mcgaw@gmail.com",
+		emoji.Sprint(":coffee: ") + "Slack? Join from the Slack button on Github",
+		emoji.Sprint(":money_with_wings: ") + "Help me? https://github.com/sponsors/qdm12",
+	}
+}