New implementation of long variable names. Each variable has a

New implementation of long variable names.  Each variable has a
"normal" name, which may be up to 64 bytes long and which is used
for all normal operations.  Variables may have a "short" name,
which is limited to 8 bytes and used only for system and portable
file input and output.

Make tokid case-preserving.  Update most uses of tokid to treat it
case-insensitively.

Update many commands to deal with long variable names.