+### get_all_threads () ##########################################################
+#
+# Read and Parse the main file (without any XML-module, they are too slow)
+#
+# Params: $file /path/to/filename of the main file
+# $deleted hold deleted (invisible) messages in result (1) oder not (0)
+# $sorted direction of message sort: descending (0) (default) or ascending (1)
+# Return: scalar context: hash reference
+# list context: list (\%threads, $last_thread, $last_message, \@unids)