Add shebang support (#149)

Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>

CLI/FileUtils.cpp

@@ -67,6 +67,10 @@ std::optional<std::string> readFile(const std::string& name)
     if (read != size_t(length))
         return std::nullopt;
 
+    // Skip first line if it's a shebang
+    if (length > 2 && result[0] == '#' && result[1] == '!')
+        result.erase(0, result.find('\n'));
+
     return result;
 }