images.loader.gtk: fix fall-through in case problem in image>GdkPixbuf
images.loader.tests: restructure the tests because the gtk linux backend doesn't handle some formats that the windows backend does
io.streams.peek: Add file position indicator api calls.
fuel.eval: wrap fuel-pprint in a without-limits so fuel output isn't truncated
magic: bindings for libmagic.
magic: some minor fixes.
magic.ffi: look for "magic" (works better on linux).
io.launcher.windows: Make unit tests show that process fails rather than
reporting bogus error. Fixes #1152 (it wasn't really a bug, just bad
tests).
compiler.cfg.linear-scan: experimental change, trying to prove that
ebp (frame-reg) doesnt need to be saved ever