Improved naming of Header constructor

`from_record` is now called `with_record` as the library standard
suggests

src/headparse.rs

@@ -410,7 +410,7 @@ impl Header {
     /// 
     /// Initializes the signal_specs vector with the correct capacity provided
     /// by the record.
-    fn from_record(record: Record) -> Header {
+    fn with_record(record: Record) -> Header {
         let capacity = record.signal_count;
         Header { record: Some(record), signal_specs: Vec::with_capacity(capacity) }
     }
@@ -448,7 +448,7 @@ pub fn parse_header(header_data: &str) -> Result<Header, &str> {
             match possible_record {
                 Ok(rec) => {
                     specs_max = rec.signal_count;
-                    header = Header::from_record(rec);
+                    header = Header::with_record(rec);
                     found_record = true;
                     continue;
                 }