Initial commit: Schunix as it stands before the SchOS rename

An x86-64 operating system built from xv6, now largely rewritten: SMP,
a copy-on-write root filesystem (SchFS), PCI/USB/virtio drivers, a TTF
rasteriser, and a Linux-numbered syscall ABI.

No history before this point -- the tree was never under version control.
This commit exists so the rename that follows has something to undo to.

.gitattributes

@@ -0,0 +1,18 @@
+# Keep LF in the working tree, on Windows included.
+#
+# Git's autocrlf would otherwise rewrite line endings on checkout, and this
+# tree does not tolerate that: the build runs under Git Bash, and a Makefile
+# recipe or a .S file with CRLF fails in ways that point nowhere near the
+# actual cause.
+* text eol=lf
+
+# Binary, never touched.
+*.png     binary
+*.jpg     binary
+*.ttf     binary
+*.img     binary
+*.iso     binary
+*.tar.gz  binary
+*.tgz     binary
+*.zip     binary
+*.wad     binary