Move version module

It's only used inside the function module, so move it there.

src/function/eval.rs

@@ -7,7 +7,7 @@ use std::path::{Path, PathBuf};
 use regex::Regex;
 
 use super::{ComparisonOperator, Function};
-use crate::version::Version;
+use super::version::Version;
 use crate::{Error, State};
 
 fn add_extension(path: &Path, extension: &str) -> PathBuf {

src/function/mod.rs

@@ -6,6 +6,7 @@ use std::path::PathBuf;
 use regex::Regex;
 use unicase::eq;
 
+mod version;
 pub mod eval;
 pub mod parse;
 

src/lib.rs

@@ -1,6 +1,5 @@
 mod error;
 mod function;
-mod version;
 
 use std::collections::{HashMap, HashSet};
 use std::ffi::OsStr;