updated for version 7.4.539
Problem:    Crash when computing buffer count.  Problem with range for user
	    commands.  Line range wrong in Visual area.
Solution:   Avoid segfault in compute_buffer_local_count().  Check for
	    CMD_USER when checking type of range. (Marcin Szamotulski)
Added tag v7-4-539 for changeset 77fe94082f53