Fix mishandling of blank lines

Author: istathar

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "technique"
-version = "0.4.1"
+version = "0.4.2"
 edition = "2021"
 description = "A domain specific language for procedures."
 authors = [ "Andrew Cowie" ]

Cargo.toml

@@ -967,6 +967,12 @@ impl<'i> Parser<'i> {
         let mut elements = vec![];
 
         while !parser.is_finished() {
+            parser.trim_whitespace();
+
+            if parser.is_finished() {
+                break;
+            }
+
             let content = parser.source;
 
             if is_procedure_title(content) {