[boost] Adding some image libs to boost build

I have added jpeg, png, and tiff jam files to boost trunk. These files will be needed by gil::io tests. There are still some remaining issues which I like to discuss in this thread: 1. building these libs sometimes requires renaming header and/or source files to the correct architecture. Should we leave that up to the user or should bjam take care of it. And if so, how will we configure that. One example is jpeg: see jconfig.vc -> jconfig.h 2. Tiff has a file nmake.opt which is included in the makefile. How will we include all those options? Regards, Christian