NtfLog plugin

-Changed block log database error reporting to be less verbose
-Tweaked how rollback and redo make sure only one block change is reversed/redone per location. Originally, nested maps were used to identify repeat locations. This version implements a Point3d class that overrides the "hashCode" and "equals" object methods so that it can be used in a Set to accomplish the same thing (in presumably less time).
-Built with the newer Derby 10.9.1.0

For memory efficiency, only about 10 changes will be kept for any particular block.*

*The number recorded can actually be a bit higher than 10, since the ceiling for a deletion operation is actually 14 changes. In other words,
 the system won't actually delete any recorded changes until there are 14 or more changes for a particular block.