(scan_separators): Support all character escape

(scan_separators): Support all character escape
sequences supported by gcc.
(find_entries): rewind unconditionally.
(find_entries): Do not call language functions directly, now calls
itself.
(find_entries): Do general initialisations here.
(CNL_SAVE_DEFINEDEF, C_entries, LOOP_ON_INPUT_LINES, F_getit)
(Ada_getit, Pascal_functions, Pascal_functions)
(prolog_skip_comment): Do not do them here.
(readline_internal): Increment lineno here.
(readline): Conditionally undo readline_internal increment.
(readline): Do not return a value.