Add PUA mappings for separated 4-cell graphics

Add PUA mappings for separated 4-cell graphics

I'm a bit uncertain about this because I currently think these glyphs
shouldn't be in Bedstead at all.  They're not based on any real system
or standard, so they don't really have any good reason to be here.
But here they are nonetheless, at least until Bedstead 003.000.  So
while I don't really want to encourage their use, I think gratuitously
leaving them difficult to use will just annoy anyone who actually has
a use for them and they thus deserve encodings.