Add deprecated net.imglib2.multithreading package

This code was removed from imglib2 core for the 2.0.1 release, but is
still in use by imglib2-algorithm.

As discussed at the October 2014 Madison ImgLib2 hackathon, the eventual
plan is to improve scijava-common's org.scijava.thread package to have
baseline multithreading interface(s), which would be used here in
imglib2-algorithm, in imagej-ops, and elsewhere as appropriate for
supporting multithreading computation.

First, though, we want to study the new constructs of Java 8, such as
java.util.Spliterator, as well as third party libraries
(quartz-scheduler.org, perhaps) and Scala (scala.concurrent package).
Update to imglib2 2.0.1

This updates the POM to use the standalone pom-imglib2 parent.
We no longer need to declare most versions, since they are managed.

The artifact was renamed to imglib2-algorithm (from imglib2-algorithms)
for consistency with its package prefix. Because of that, we can start
the versioning over at 0.1.0, which according to SemVer indicates the
initial incubation period of development.

This commit also updates the code as necessary to address backwards
incompatible changes to the ImgLib2 library in the wake of the release.
Ignore Eclipse metadata and Maven build directory
Add a mailmap to improve "git shortlog -nse"