cache elementwise kernels

reference:
http://lists.tiker.net/pipermail/pycuda/2011-September/003416.html
http://article.gmane.org/gmane.comp.python.cuda/2424

I am also trying to deploy pycuda on non-admin machines.
I am able to use SourceModule based kernels using the cache_dir option to it.
However, elementwise kernels seem to use #includes and unconditionally runs external compilers.

what do you think of having two compiler cache options: 1. based on preprocessed source, 2. based on postprocessed source.
if one is messing with headers, they could just use the postprocessed cache option.
For deployment, we could use preprocessed cache option, and ship the preprocessed cache dir.

if you are ok with this, i can go ahead and implement my suggestion and send a pull request.
Thanks for making pycuda and pyopencl.
Naveen