update header copyright string
Share the definition of Events and Streams between driver and runtime APIs

As of CUDA-3.1, these data structures are equivalent and can be freely shared between both APIs. Although this drops support for very old versions of CUDA, we can --- with good conscience --- use libraries such as CUFFT and CUBLAS which are written using the runtime API, from applications such as Accelerate which use the driver API.
wibbles
add changelog
use the C enum rather than our own #c block
texture reads can perform sRGB -> linear conversion

unknown which version this was introduced
oops, JITFallback was never exported...
haddock wibbles