Opencl datahandling

Closes #15 (closed)

OpenCL kernels are now integrated in the normal create_kernel workflow. Also there exists a created a opencljit.init_globally function that just creates some CL queue/contex if you do not want to give it as a parameter to every kernel.

SerialDatahandling is extended to work with alternative GPU array libraries to PyCuda. There is now some overlapping code with the _custom_transfer_functions but I suppose they are for certain quantities that have a separate transfer function as oppose to using a whole different backend.

@kuron can you have a look on it? I think the solution is not as elegant as I thought it would be. pycuda.gpuarray.GPUArrays are not wrapped. So if you use dh.gpuarrays['foo'] you get either a pycuda array or a opencl array. I thought this step would be to drastic for one PR. Using OpenCL should still be a lot easier now.

pystencils/backends/cbackend.py

@@ -5,6 +5,7 @@ import numpy as np
 import sympy as sp
 from sympy.core import S
 from sympy.printing.ccode import C89CodePrinter
+
 from pystencils.astnodes import KernelFunction, Node
 from pystencils.cpu.vectorization import vec_all, vec_any
 from pystencils.data_types import (
@@ -344,6 +345,9 @@ class CustomSympyPrinter(CCodePrinter):
         result = super(CustomSympyPrinter, self)._print_Piecewise(expr)
         return result.replace("\n", "")
 
+    def _print_Type(self, node):
+        return str(node)
+
     def _print_Function(self, expr):
         infix_functions = {
             bitwise_xor: '^',
@@ -356,7 +360,7 @@ class CustomSympyPrinter(CCodePrinter):
             return expr.to_c(self._print)
         if isinstance(expr, reinterpret_cast_func):
             arg, data_type = expr.args
-            return "*((%s)(& %s))" % (PointerType(data_type, restrict=False), self._print(arg))
+            return "*((%s)(& %s))" % (self._print(PointerType(data_type, restrict=False)), self._print(arg))
         elif isinstance(expr, address_of):
             assert len(expr.args) == 1, "address_of must only have one argument"
             return "&(%s)" % self._print(expr.args[0])