Include documentation in printed config files (#41)

* Start work on printing toml config with comments

* WIP: toml_config: extract default values for fields

* WIP: toml_config: handle single-level nested structs

* WIP: toml_config: improve comment handling, std type trait impls

* WIP: toml_config: add Private trait, improve comment handling, clean up

* toml_config: fix default value bug; improve tests

* Use toml_config in all applicable crates; add toml_config enum support

* toml_config: improve comments

* toml_config_derive: support enum comments

* Improve config comments for udp, cli_helpers, common

* Improve config comments

* Add tests for Config struct TomlConfig implementations

* Improve Config comments

* Improve Config comments

* ws, http: add config comments for tls cert and private key lines

* small fixes to toml_config and toml_config_derive

* Run cargo fmt

* Fix typo in several config comments

* Update README

* Update README

toml_config/tests/test.rs

@@ -0,0 +1,46 @@
+use serde::Deserialize;
+
+use toml_config::{gen_serialize_deserialize_test, TomlConfig};
+
+#[derive(Clone, Debug, PartialEq, Eq, TomlConfig, Deserialize)]
+struct TestConfigInnerA {
+    /// Comment for a
+    a: String,
+    /// Comment for b
+    b: usize,
+}
+
+impl Default for TestConfigInnerA {
+    fn default() -> Self {
+        Self {
+            a: "Inner hello world".into(),
+            b: 100,
+        }
+    }
+}
+
+/// Comment for TestConfig
+#[derive(Clone, Debug, PartialEq, Eq, TomlConfig, Deserialize)]
+struct TestConfig {
+    /// Comment for a that stretches over
+    /// multiple lines
+    a: String,
+    /// Comment for b
+    b: usize,
+    c: bool,
+    /// Comment for TestConfigInnerA
+    inner_a: TestConfigInnerA,
+}
+
+impl Default for TestConfig {
+    fn default() -> Self {
+        Self {
+            a: "Hello, world!".into(),
+            b: 100,
+            c: true,
+            inner_a: Default::default(),
+        }
+    }
+}
+
+gen_serialize_deserialize_test!(TestConfig);