SVF: clean up, mostly for TAP state name handling

- Use the name mappings all the other code uses:
    + name-to-state ... needed to add one special case
    + state-to-name
 - Improve various diagnostics:
    + don't complain about a "valid" state when the issue
      is actually that it must be "stable"
    + say which command was affected
 - Misc:
    + make more private data and code be static
    + use public DIM() not private dimof()
    + shorten the affected lines

Re the mappings, this means we're more generous in inputs we
accept, since case won't matter.  Also our output diagnostics
will be a smidgeon more informative, saying "RUN/IDLE" not
just "IDLE" (emphasizing that there can be side effects).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

TODO

@@ -46,7 +46,6 @@ This section list issues that need to be resolved in the JTAG layer.
 The following tasks have been suggested for cleaning up the JTAG layer:
 
 - use tap_set_state everywhere to allow logging TAP state transitions
-- rename other tap_states to use standard JTAG names (suggested by ML)
 - Encapsulate cmd_queue_cur_state and related varaible handling.
 - add slick 32 bit versions of jtag_add_xxx_scan() that avoids
 buf_set_u32() calls and other evidence of poor impedance match between