[feat] serde support and Symbol enum variants (#23)

* [build] serde_json deps for enums

* [feat] add Symbol enum options and serde support

* [fix] cargo fmt and clippy linting

* [docs] update lib header docstring

* [tests] From<Symbol> unit tests for new variants

* [tests] underscore all From<Symbol> tested?

* [tests] full coverage for From<Symbol> trait

* [tests] full coverage

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "padder"
-version = "1.1.0"
+version = "1.2.0"
 edition = "2021"
 description = "Highly efficient data and string formatting library for Rust."
 authors = [
@@ -29,10 +29,16 @@ crate-type = [ "lib" ]
 [dependencies]
 env_logger = "0.11.0"
 log = "0.4.20"
+serde = { version = "1.0.201", features = ["derive"], optional = true }
+serde_json = { version = "1.0.117", optional = true }
 
 [dev-dependencies]
 criterion = "0.5.1"
 
+[features]
+default = []
+serde = [ "dep:serde", "dep:serde_json" ]
+
 [[bench]]
 name = "bench_main"
 harness = false