Add command timeline-tag to search for statuses matching the tag.

Since `search` only return the list of tags matching the search, this is
helpful to actually see the statuses for a particular tag.

cmd/mstdn/cmd_timeline.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"context"
+	"errors"
+	"strings"
 
 	"github.com/mattn/go-mastodon"
 	"github.com/urfave/cli/v2"
@@ -66,3 +68,23 @@ func cmdTimelineDirect(c *cli.Context) error {
 	}
 	return nil
 }
+
+func cmdTimelineHashtag(c *cli.Context) error {
+	if !c.Args().Present() {
+		return errors.New("arguments required")
+	}
+        local := c.Bool("local")
+	tag := strings.TrimLeft(argstr(c), "#")
+
+	client := c.App.Metadata["client"].(*mastodon.Client)
+	config := c.App.Metadata["config"].(*mastodon.Config)
+	timeline, err := client.GetTimelineHashtag(context.Background(), tag, local, nil)
+	if err != nil {
+		return err
+	}
+	s := newScreen(config)
+	for i := len(timeline) - 1; i >= 0; i-- {
+		s.displayStatus(c.App.Writer, timeline[i])
+	}
+	return nil
+}