Build class files somewhere besides the source directories! And (nearly) incremental builds. [1423]

This has been driving me crazy for way, way too long. Having ".class"
and ".java" files in the same directory is an abomination! Now Ant will
build class files in "build/antbuild" (the subdirectory is to avoid
potential conflicts with common IDE settings).

"Incremental" building avoids needless copying/recompiling (when
possible). However, mcidasv.jar and local-idv.jar always have changes
to their manifests and are always rebuilt… :(