Hackery for Mac OS X.

For whatever foolish reason, Apple decided to use .jnilib for JNI native
libraries, even though they're actually just .dylib files. When they handed all
their source over to Oracle and said "please to maintain", Oracle decided that
using .jnilib was retarded, so they stopped supporting it. Smack dab in the
middle of the lifecycle for Java 7 apparently. There was hue and cry and they
claimed they were going to reinstate .jnilib support (for Java 7 anyway) but
that has apparently not happened. So .jnilib works on some versions of Java 7
but not others. Sigh.

We just copy any .jnilib files (which LWJGL uses) to .dylib files so that both
exist (ensuring that things work for Java 6, Java 7 and Java 8).
Nixed SBT build.

SBT is dead to me (mostly).