generic Entity parse

Allow multiple entity implementations to enabled simultaneously, select which one to use with generics.

examples/parse.rs

@@ -7,7 +7,7 @@ fn main() -> Result<(), vbsp::BspError> {
     let data = std::fs::read(args.next().expect("No demo file provided"))?;
     let bsp = vbsp::Bsp::read(&data)?;
     for prop in bsp.entities.iter() {
-        match prop.parse() {
+        match prop.parse::<vbsp::Entity>() {
             Ok(prop) => {
                 println!("{:#?}", prop)
             }

src/data/entity.rs

@@ -114,7 +114,7 @@ impl<'a> RawEntity<'a> {
         Some(T::parse(self.prop(key)?))
     }
 
-    pub fn parse(&self) -> Result<Entity<'a>, VdfError> {
+    pub fn parse<E: Deserialize<'a>>(&self) -> Result<E, VdfError> {
         vdf_reader::from_str(self.buf)
     }
 }