Move code from egui_demo_lib to egui_demo_app (#1540)

Also clean up feature names and dependencies

egui_extras/CHANGELOG.md

@@ -5,6 +5,7 @@ All notable changes to the `egui_extras` integration will be noted in this file.
 ## Unreleased
 * Added `Strip`, `Table` and `DatePicker` ([#963](https://github.com/emilk/egui/pull/963)).
 * MSRV (Minimum Supported Rust Version) is now `1.60.0` ([#1467](https://github.com/emilk/egui/pull/1467)).
+* Renamed feature "persistence" to "serde" ([#1540](https://github.com/emilk/egui/pull/1540)).
 
 
 ## 0.17.0 - 2022-02-22

egui_extras/Cargo.toml

@@ -26,14 +26,13 @@ all-features = true
 [features]
 default = []
 
-# Support loading svg images
-svg = ["resvg", "tiny-skia", "usvg"]
-
 # Datepicker widget
 datepicker = ["chrono"]
 
-# Persistence
-persistence = ["serde"]
+serde = ["dep:serde"]
+
+# Support loading svg images
+svg = ["resvg", "tiny-skia", "usvg"]
 
 # Log warnings using `tracing` crate
 tracing = ["dep:tracing", "egui/tracing"]
@@ -57,7 +56,7 @@ resvg = { version = "0.22", optional = true }
 tiny-skia = { version = "0.6", optional = true }
 usvg = { version = "0.22", optional = true }
 
-# feature "persistence":
+# feature "serde":
 serde = { version = "1", features = ["derive"], optional = true }
 
 # feature "tracing"

egui_extras/src/datepicker/button.rs

@@ -3,7 +3,7 @@ use chrono::{Date, Utc};
 use egui::{Area, Button, Frame, Key, Order, RichText, Ui, Widget};
 
 #[derive(Default, Clone)]
-#[cfg_attr(feature = "persistence", derive(serde::Deserialize, serde::Serialize))]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 pub(crate) struct DatePickerButtonState {
     pub picker_visible: bool,
 }

egui_extras/src/datepicker/popup.rs

@@ -4,7 +4,7 @@ use chrono::{Date, Datelike, NaiveDate, Utc, Weekday};
 use egui::{Align, Button, Color32, ComboBox, Direction, Id, Layout, RichText, Ui, Vec2};
 
 #[derive(Default, Clone)]
-#[cfg_attr(feature = "persistence", derive(serde::Deserialize, serde::Serialize))]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
 struct DatePickerPopupState {
     year: i32,
     month: u32,