Compile PDF quietly

Signed-off-by: Peter Hatina <peter@hatina.eu>

lib/invoice/cli.py

@@ -206,8 +206,9 @@ class Application:
             assert(os.path.exists(tex_file))
 
             log.debug("Creating PDF invoice...")
-            if subprocess.call((self.tex_program, "{0}.tex".format(invoice._name)), cwd=tmp_path) != 0:
-                raise GenerationError("PDF generation failed.")
+            with open(os.devnull, 'w')  as FNULL:
+                if subprocess.call((self.tex_program, "{0}.tex".format(invoice._name)), cwd=tmp_path, stdout=FNULL) != 0:
+                    raise GenerationError("PDF generation failed.")
             assert(os.path.exists(tmp_pdf_file))
 
             log.debug("Moving PDF file to the output directory...")