#468 OpenCL code to weave segments into partitions

[Marco da Silva Domingues]

Hi,
This patch contains the OpenCl code to weave segments into partitions, using a bitvector of 32 bits to represent the segments in each partition.

Tested the code with CSG scenes containing union, difference and intersection operations and the results matched the results from the Ansi C code.

[Marco da Silva Domingues]

Removed the pointers from the cl_partition structure and added some relevant comments in the code

[Marco da Silva Domingues]

Weave of segs using a dynamic bitarray to represent the segments in each partition. Changed the cl_partition structure in order to simulate a double linked list, which should optimize the insertion of partition