Misc Improvements to GPU Package

- Optimizations for molecular systems
-   Improved kernel performance and greater CPU overlap
- Reduced GPU to CPU communications for discrete devices
- Switch classic Intel makefiles to use LLVM-based compilers
- Prefetch optimizations supported for OpenCL
- Optimized data repack for quaternions

lib/gpu/lal_device.cu

@@ -52,4 +52,5 @@ __kernel void kernel_info(__global int *info) {
   info[16]=MAX_SHARED_TYPES;
   info[17]=MAX_BIO_SHARED_TYPES;
   info[18]=PPPM_MAX_SPLINE;
+  info[19]=NBOR_PREFETCH;
 }