(XTmouse_position, x_term_init):

(XTmouse_position, x_term_init):
Save value of x_catch_errors and pass to x_uncatch_errors.

(x_catch_errors): Use specpdl so can be nested.
Use a Lisp string to as the buffer for the X message.
(x_uncatch_errors, x_had_errors_p, x_check_errors): Related changes.
(x_catch_errors_unwind): New function.
(x_error_quitter): Call x_error_catcher if appropriate.
(x_error_message_string): New variable.
(syms_of_xterm): Defvar it.
(x_caught_error_message): Variable deleted.
(X_ERROR_MESSAGE_SIZE): Renamed from X_CAUGHT_ERROR_MESSAGE_SIZE.
(x_error_handler): New function, calls x_error_quitter or ..._checker.
(x_initialize): Use x_error_handler as error handler for X.