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 netsurf.h header should *only* contain the registration, core
initialisation and finalisation methods. Version information is best
placed in its own header.
Also remove any unneeded inclusion of this header limiting it to
solely the places the relevant API is required.
