Include ldg files instead of appending

Do not use dcontext for precision for now. It does not seem
to be necessary.

src/toldg/process.py

@@ -1,6 +1,7 @@
 import csv
 import datetime
 import logging
+import os
 import re
 import sys
 
@@ -12,10 +13,11 @@ from toldg.models import Config, CsvConfig, Mapping, Transaction
 
 
 def process_ldg_files(config: Config):
-    for ldg_file in toldg.utils.get_ldg_files(config.input_directory):
-        with open(ldg_file, "r") as f_in:
-            with open(config.output_file, "a") as f_out:
-                f_out.write(f_in.read())
+    with open(config.output_file, "a") as f_out:
+        f_out.write("\n")
+        for ldg_file in toldg.utils.get_ldg_files(config.input_directory):
+            ldg_rel = os.path.relpath(ldg_file, os.path.dirname(config.output_file))
+            f_out.write(f"include \"{ldg_rel}\"\n")
 
 
 def get_csv_config(csv_file: str, csv_configs: list[CsvConfig]) -> CsvConfig: