recent changes

Hi, these are the recent changes (available from the latest snapshot)

* tla add now continues to add files even when reaching an error on an
existing file.  This is useful when you are adding files and you have
added some files but not others.  For example,

tla add main.c
tla add *.c

on the second run, the previous behavior is to abort with a message
that main.c already in the archive.  The new behavior is to continue
to add other .c files.

* tla commit now allows the exclusion of files via the -x option.  For example,

tla commit -x main.c

will commit every file but main.c

tla commit -x a.c  -- b.c a.c d.c

will commit b.c and d.c

* tla library-path is an alias for tla my-revision-library,  setting
the location (path) of the revision library.
* tla archive-create is an alias for tla make-archive.

Regards,
Andy