If you have a single line selected, Set Address adds a .ORG directive
that changes the addresses of all following data, until the next .ORG
directive is reached. Sometimes code will relocate part of itself,
and it's useful to be able to set the address at the end of the block
to what it would have been before the .ORG change.
If you have multiple lines selected, we now add the second .ORG to
the offset that follows the last selected line.
Also, fixed a bug in the Symbol value updater that wasn't handling
non-unique labels correctly.
The current AddressMap is now passed into the plugin manager, which
wraps it in an AddressTranslate object and passes that to the
plugins at Prepare() time. This allows plugins to convert addresses
to offsets, making it possible to format complex structures.
This breaks existing plugins.
