SUPERSEDE option to OPEN

[Tovar <TVR@CCRMA-F4.Stanford.Edu>]

My apologies if this was fixed in 2.0.  I would appreciate it if OPEN would
accept :SUPERCEDE as well as :SUPERSEDE to :IF-EXISTS.  NeXT's Webster's claims
it is merely a variation in spelling.  This is a bug which could easily escape
even a careful reading of one's code, and might only bite under extraordinary
conditions, such as creating a file to write out a error report.  Would anyone
be bothered by the few extra words it take to accept both keywords?
								     -- Tovar