This changes the LOG macro to be varadic removing the need for all
callsites to have double bracketing and allows for future improvement
on how we use the logging macros.
The callsites were changed with coccinelle and the changes checked by
hand. Compile tested for several frontends but not all.
A formatting annotation has also been added which allows the compiler
to check the parameters and types passed to the logging.
The windows win32 frontend bitmap creation was ignoring the creation
flags, specifically those related to bitmap opacity so was plotting
images as transparent even if they had no alpha channel values set.
