updated for version 7.4a.041
Problem:    When using ":new ++ff=unix" and "dos" is first in 'fileformats'
	    then 'ff' is set to "dos" instead of "unix". (Ingo Karkat)
Solution:   Create set_file_options() and invoke it from do_ecmd().
Added tag v7-4a-041 for changeset 74d2f3188cd0