OpenCL (oclcl) on Petalisp

This is a slow but functioning backend for Petalisp that can utilise a graphics card to theoretically run Petalisp code which deals only in real numerical arrays faster than on a CPU.

Dependencies

These can, and probably should, be obtained from Quicklisp:

• Petalisp for some really weird reason
• oclcl for generating OpenCL code

This cannot be obtained from Quicklisp:

• eazy-opencl for running OpenCL code

Cloning eazy-opencl into ~/quicklisp/local-projects will allow you to load it with Quicklisp.

Bugs

• I have witnessed a few "random" memory faults over many computations, which is scary. This might have to do with how eazy-opencl deals with device memory, and how it depends on finalisers which a garbage collector with little work to do will seldom run. It is also unclear how to manually free said device memory.
• Reduction is supposed to occur over a binary tree, instead of linearly like CL:REDUCE. In "concrete" terms, this means we should compute f(f(x1, x2), f(x3, x4)) instead of f(f(f(x1, x2), x3), x4), for a function f and values x1 through x4. haha no 🦎REDUCTIONS🦎ARE🦎GONE🦎🦎🦎