Workaround template functions not loaded

This is a hacky workaround to make things work until we find a better
solution.

Closes: https://todo.sr.ht/~emersion/alps/96

plugins/base/template.go

@@ -3,11 +3,17 @@ package alpsbase
 import (
 	"html/template"
 	"net/url"
+	"strings"
 	"time"
 
 	"github.com/emersion/go-imap"
 )
 
+const (
+	inputDateLayout = "2006-01-02"
+	inputTimeLayout = "15:04"
+)
+
 var templateFuncs = template.FuncMap{
 	"tuple": func(values ...interface{}) []interface{} {
 		return values
@@ -40,4 +46,19 @@ var templateFuncs = template.FuncMap{
 			return true
 		}
 	},
+	"join": func(l []string, sep string) string {
+		return strings.Join(l, sep)
+	},
+	"formatinputdate": func(t time.Time) string {
+		if t.IsZero() {
+			return ""
+		}
+		return t.Format(inputDateLayout)
+	},
+	"formatinputtime": func(t time.Time) string {
+		if t.IsZero() {
+			return ""
+		}
+		return t.Format(inputTimeLayout)
+	},
 }

plugins/caldav/plugin.go

@@ -2,10 +2,8 @@ package alpscaldav
 
 import (
 	"fmt"
-	"html/template"
 	"net/http"
 	"net/url"
-	"time"
 
 	"git.sr.ht/~emersion/alps"
 )
@@ -64,21 +62,6 @@ func newPlugin(srv *alps.Server) (alps.Plugin, error) {
 
 	registerRoutes(&p, u)
 
-	p.TemplateFuncs(template.FuncMap{
-		"formatinputdate": func(t time.Time) string {
-			if t.IsZero() {
-				return ""
-			}
-			return t.Format(inputDateLayout)
-		},
-		"formatinputtime": func(t time.Time) string {
-			if t.IsZero() {
-				return ""
-			}
-			return t.Format(inputTimeLayout)
-		},
-	})
-
 	return p.Plugin(), nil
 }
 

plugins/carddav/plugin.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"net/http"
 	"net/url"
-	"strings"
 
 	"git.sr.ht/~emersion/alps"
 	alpsbase "git.sr.ht/~emersion/alps/plugins/base"
@@ -112,12 +111,6 @@ func newPlugin(srv *alps.Server) (alps.Plugin, error) {
 
 	registerRoutes(p)
 
-	p.TemplateFuncs(map[string]interface{}{
-		"join": func(l []string, sep string) string {
-			return strings.Join(l, sep)
-		},
-	})
-
 	p.Inject("compose.html", func(ctx *alps.Context, _data alps.RenderData) error {
 		data := _data.(*alpsbase.ComposeRenderData)