[settings] Use a generic setting's own type as its default type
When fetching a named setting using a name that does not explicitly
specify a type, default to using the type stored when the setting was
created, rather than always defaulting to "string". This allows the
behaviour of user-defined settings to match the behaviour of
predefined settings (which have a sensible default type).
For example:
set server:ipv4 192.168.0.1
echo ${server}
will now print "192.168.0.1", rather than trying to print out the raw
IPv4 address bytes as a string.
The downside of this change is that existing tricks for printing
special characters within scripts may require (backwards-compatible)
modification. For example, the "clear screen" sequence:
set esc:hex 1b
set cls ${esc}[2J
echo ${cls}
will now have to become
set esc:hex 1b
set cls ${esc:string}[2J # Must now explicitly specify ":string"
echo ${cls}
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Michael Brown