Remove no-longer needed import

Besides, we'd like to take out CodeHacker from the public API of
ij1-patcher (so we do not have to maintain backwards-compatible changes
should we decide to change it).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
ij-legacy: start using properties for the ij1-patcher dependency

Just like all other dependencies, we will want the groupIds and versions
to be specified in pom-scijava. In preparation, we use them in the
definition of the dependency already.

While at it, use the first ij1-patcher release version ever.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>