OpenCL error in fractal_core_shell

[butler]

while working through ticket #792 I discovered that fractal_core_shell.c is receiving 0.0 for thickness rather than the input from the defaults in fractal_core_shell.py or as changed from the GUI. Went back and verified this is true for the latest development build (windows 7 build 601). This is verified on my laptop which claims from the log file:

 OpenCL Intel(R) HD Graphics 4400

I then downloaded the same to my non openCL machine and it does not appear to be passing 0 thickness given the behavior. Thus it seems to be a problem with the C code for OpenCL.

Furhter version 4.01 on the same openCL laptop also does not seem to have the problem of passing 0 thickness so it must have been introduced since 4.01