feat(value): Create to_value

`to_value` lets any `impl Serialize` convert to a liquid_value::Value.

This can be useful for creating the globals needed for the parser.

liquid-value/Cargo.toml

@@ -15,9 +15,11 @@ travis-ci = { repository = "cobalt-org/liquid-rust" }
 appveyor  = { repository = "johannhof/liquid-rust" }
 
 [dependencies]
+num-traits = "0.2"
 # Exposed in API
 chrono = "0.4"
 serde = { version = "1.0", features = ["derive"] }
+liquid-error = { version = "0.15.0", path = "../liquid-error" }
 
 [dev-dependencies]
 difference = "2.0"

liquid-value/src/lib.rs

@@ -7,11 +7,20 @@
 #[macro_use]
 extern crate serde;
 extern crate chrono;
+extern crate liquid_error;
+extern crate num_traits;
 
 mod index;
 mod scalar;
+mod ser;
 mod values;
 
+/// Liquid Processing Errors.
+pub mod error {
+    pub use liquid_error::*;
+}
+
 pub use index::*;
 pub use scalar::*;
+pub use ser::*;
 pub use values::*;