#43 cannot write to GenJ database

[Daniel Kionka]

GenJ now has a transaction model for changes. The
interface has to start a transaction before changing any
properties and then end it when done.

Reports still work because they are read-only.

There is a subtle bug when browsing with BKEdit. It
fails with the missing transation when simply viewing an
address. GenJ hides continuation lines by combining
all values into a single string with newlines. When you
have an address, it is automatically converted to
separate lines for the address window, and this is seen
as a change, and it tries writing it back. We should
never change data just by viewing it, but GenJ is
cheating by combining lines. The interface should
create virtual continuation lines to hide the "feature" of
removing the continuation lines.