2010-07 snapshot tagged

Yet another snapshot has been tagged. Binaries will be uploaded soon. As mentioned previously, a cross-compile is needed for this snapshot. You can use 20a/boot-2010-06-cross-x86.lisp to do the cross-compile on x86. For others, just use the standard script in tools/cross-scripts. This snapshot fixes an annoying bug in sse2 where trace returned incorrect values for floating-point arguments. This also adds two new slots to an fd-stream that will be used later to allow handling of encoding/decoding errors for external formats. Ray