Add --json flag to be used by editor extensions (#936)

internal/editors/output.go

@@ -0,0 +1,14 @@
+package editors
+
+// Output wraps task list output for use in editor integrations (e.g. VSCode, etc)
+type Output struct {
+	Tasks []Task `json:"tasks"`
+}
+
+// Task describes a single task
+type Task struct {
+	Name     string `json:"name"`
+	Desc     string `json:"desc"`
+	Summary  string `json:"summary"`
+	UpToDate bool   `json:"up_to_date"`
+}