update device extension check to test for empty array
fix test failures as julia now returns substrings from string operations
Throw More Specific Error Messages

This change tries to substitute generic uses of error for more
specific error messages.  Two new Error Objects were introduced.
OpenCL.OpenCLException is for generic library runtime errors.
OpenCL.CLMemoryError is for possible double free events of subtypes
of CLMemObject
add enqueue_map/unmap
Merge branch 'master' of git://github.com/jakebolewski/OpenCL.jl
add show for buffers
reformatting tweaks
add map/unmap buffer functions
numba like kernel call syntax
support opencl tasks
update examples to reflect new kernel call syntax
fix merge conflict for demo.jl
add comments, keep track of hostbuf pointer to raise error when trying to unmap an array not tied to a particular buffer
fix errors with initializing buffers with hostptr, add test
remove TODO
correct macro spelling
check for device maximum work size in kernel call
update README to point out clcompiler work
missing paren
Merge branch 'master' into clcompiler