Expand Delite's LAPACK support to non-MKL versions of LAPACK

[chrisdesa]

This update allows OptiML programs to use LAPACKE routines on machines that don't have MKL. It needs to be used together with the parallel update to Delite. It makes the following changes:

• Adds primal-dual interior point solver app.
• Modifies all references to MKL_INT to lapack_int.
• Modifies all object references to external library "MKL" to "LAPACK".
• Removed MKL.xml config file, and added three new LAPACK.xml config files, one for each supported platform: MKL, ubuntu free-software lapacke, and apple accelerate.
• Changed ExternalLibrary class to use a shell invocation to compile the external libraries, which allows us to use environment variables in the external library configuration XML files.
• Changed ExternalLibrary class to list the external libraries last in the compiler invocation, which is necessary to compile the LAPACK library on Ubuntu (hopefully this doesn't break anything).
• Changed the MKL config file to reference the jni.h include files located within the $JAVA_HOME directory, instead of those located within Kevin's home directory. I'm not sure why we weren't doing this in the first place, so maybe this change is wrong.

[asujeeth]

I'd like to separate out the PDIP solver stuff from the LAPACK updates. For this pull request, let's just pull in the LAPACK stuff. I can either merge and remove the PDIP stuff, or you can submit a clean pull request which just the LAPACK changes.

[asujeeth]

Nevermind, I just moved things around slightly.