Fixed regex error and added ensured all area is backed up

+ the regex to match region files was only matching one number
+ ensured the save radius includes all blocks requested

src/main.rs

@@ -27,7 +27,7 @@ struct Region {
 
 impl Region {
     fn from_string(string: String) -> Option<Self> {
-        let re = Regex::new(r"r\.(?P<x>-?[0-9])+\.(?P<y>-?[0-9])").unwrap();
+        let re = Regex::new(r"r\.(?P<x>-?[0-9]*)+\.(?P<y>-?[0-9]*)").unwrap();
         if re.is_match(string.as_str()) {
             let captures = re.captures(string.as_str()).unwrap();
 
@@ -90,11 +90,7 @@ fn backup_region(
     backup_dir.push(dir_name);
     create_dir(&backup_dir)?;
 
-    let save_radius = if save_radius < 512 {
-        1 as i64
-    } else {
-        (save_radius / 512) as i64
-    };
+    let save_radius = (save_radius as f64 / 512.0).ceil() as i64;
 
     for entry in src_dir.read_dir()? {
         let entry = entry?;