Globally rename "jtag_nsrst_delay" as "adapter_nsrst_delay", and move it
out of the "jtag" command group ... it needs to be used with non-JTAG
transports
Includes a migration aid (in jtag/startup.tcl) so that old user scripts
won't break. That aid should Sunset in about a year.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>