Provide Verbose Message when structs are encountered as args to kernels

[steveneliuk]

See section 7 of the working draft, https://cvs.khronos.org/svn/repos/registry/trunk/public/webcl/spec/latest/index.html#7

Just so one doesnt get hung up on this in the future,

There are likely others in section 7 we should account for,

[wolfviking0]

For the moment I have a general warning when the Kernel Parse find some unknown type that include struct.

But I can't make an assert because could be work like Mandelbulb demo

[tonikitoo]

for cross-browser / platform / drive safety, assert is advisable, I would say.