* main.c: Add variables source_line_number, source_file_name,

	* main.c: Add variables source_line_number, source_file_name,
	source_error, source_error_allocated, and source_pre_error.
	(command_line_input): If source_file_name set, increment
	source_line_number and set error_pre_print with them.
	(source_command): Set source_* and make a cleanup so they get
	set back.