first usable version of kernel and commands

After an year of hard work, this is a first "usable" version of Jehanne.

qa/lib/thread/thread.c

@@ -0,0 +1,60 @@
+
+#include <u.h>
+#include <libc.h>
+#include <thread.h>
+
+enum
+{
+	STACK = 2048,
+};
+
+void
+clockproc(void *arg)
+{
+	int t;
+	Channel *c;
+
+	c = arg;
+	for(t=0;; t++){
+		sleep(100);
+		sendul(c, t);
+	}
+}
+
+
+void
+threadmain(int argc, char *argv[])
+{
+	int tick, tock;
+	Alt a[] = {
+		{nil, &tick, CHANRCV},
+		{nil, &tock, CHANRCV},
+		{nil, nil, CHANEND},
+	};
+
+	fprint(2, "threadmain hi!\n");
+
+	a[0].c = chancreate(sizeof tick, 0);
+	a[1].c = chancreate(sizeof tock, 0);
+
+	proccreate(clockproc, a[0].c, STACK);
+	proccreate(clockproc, a[1].c, STACK);
+
+	tick = 0;
+	tock = 0;
+	while(tick < 10 || tock < 10){
+		switch(alt(a)){
+		case 0:
+			fprint(2, "tick %d\n", tick);
+			break;
+		case 1:
+			fprint(2, "tock %d\n", tock);
+			break;
+		default:
+			sysfatal("can't happen");
+		}
+	}
+
+	print("PASS\n");
+	threadexitsall("PASS");
+}