feat #73: remove iffy back button on new session

Closes #73

frontend/session_view.go

@@ -26,9 +26,7 @@ func (v *SessionView) New(ctx echo.Context) string {
 		Title: "New session",
 	}, func(ctx echo.Context) g.Node {
 		return h.Div(
-			c.PageHeader("New session", cc.HeaderButtonGroup(
-				cc.NeutralButton("Back", "/"),
-			)),
+			c.PageHeader("New session"),
 			h.Form(
 				h.Method("POST"),
 				h.Action(config.SESSIONS_CONTROLLER_ROOT),

frontend/sessions_controller.go

@@ -89,6 +89,7 @@ type NewSessionsControllerParams struct {
 	SessionManager *scs.SessionManager
 	View           *SessionView
 	Mailer         *commons.Mailer
+	Flasher        *commons.Flasher
 }
 
 type NewSessionsControllerResult struct {
@@ -105,6 +106,7 @@ func NewSessionsController(p NewSessionsControllerParams) NewSessionsControllerR
 			SessionManager: p.SessionManager,
 			View:           p.View,
 			Mailer:         p.Mailer,
+			Flasher:        p.Flasher,
 		},
 	}
 }