Update texinfo documentation to match current implementation.

* check/Makefile.am: "make debug" target should pass only
	the main test tool program as argument for running gdb

	* configure.ac: Add the --enable-assertions options.

	* doc/Makefile.am, doc/body.texi, doc/lightning.texi:
	Major rewrite of the documentation to match the current
	implementation.

	* doc/version.texi: Automatic date update.

	* doc/ifib.c, doc/incr.c, doc/printf.c, doc/rfib.c, doc/rpn.c:
	Implementation of the documentation examples, that are also
	compiled during a normal build.

	* doc/p-lightning.texi, doc/porting.texi, doc/toc.texi,
	doc/u-lightning.texi, doc/using.texi: These files were
	renamed in the documentation rewrite, as the documentation
	was significantly trimmed due to full removal of the porting
	chapters. Better porting documentation should be added but
	for the moment it was just removed the documentation not
	matching the implementation.

doc/rpn.c

@@ -0,0 +1,94 @@
+#include <stdio.h>
+#include <lightning.h>
+
+typedef int (*pifi)(int);       /* Pointer to Int Function of Int */
+
+static jit_state_t *_jit;
+
+void stack_push(int reg, int *sp)
+{
+  jit_stxi_i (*sp, JIT_FP, reg);
+  *sp += sizeof (int);
+}
+
+void stack_pop(int reg, int *sp)
+{
+  *sp -= sizeof (int);
+  jit_ldxi_i (reg, JIT_FP, *sp);
+}
+
+jit_node_t *compile_rpn(char *expr)
+{
+  jit_node_t *in, *fn;
+  int stack_base, stack_ptr;
+
+  fn = jit_note(NULL, 0);
+  jit_prolog();
+  in = jit_arg();
+  stack_ptr = stack_base = jit_allocai (32 * sizeof (int));
+
+  jit_getarg_i(JIT_R2, in);
+
+  while (*expr) {
+    char buf[32];
+    int n;
+    if (sscanf(expr, "%[0-9]%n", buf, &n)) {
+      expr += n - 1;
+      stack_push(JIT_R0, &stack_ptr);
+      jit_movi(JIT_R0, atoi(buf));
+    } else if (*expr == 'x') {
+      stack_push(JIT_R0, &stack_ptr);
+      jit_movr(JIT_R0, JIT_R2);
+    } else if (*expr == '+') {
+      stack_pop(JIT_R1, &stack_ptr);
+      jit_addr(JIT_R0, JIT_R1, JIT_R0);
+    } else if (*expr == '-') {
+      stack_pop(JIT_R1, &stack_ptr);
+      jit_subr(JIT_R0, JIT_R1, JIT_R0);
+    } else if (*expr == '*') {
+      stack_pop(JIT_R1, &stack_ptr);
+      jit_mulr(JIT_R0, JIT_R1, JIT_R0);
+    } else if (*expr == '/') {
+      stack_pop(JIT_R1, &stack_ptr);
+      jit_divr(JIT_R0, JIT_R1, JIT_R0);
+    } else {
+      fprintf(stderr, "cannot compile: %s\n", expr);
+      abort();
+    }
+    ++expr;
+  }
+  jit_retr(JIT_R0);
+  jit_epilog();
+  return fn;
+}
+
+int main(int argc, char *argv[])
+{
+  jit_node_t *nc, *nf;
+  pifi c2f, f2c;
+  int i;
+
+  init_jit(argv[0]);
+  _jit = jit_new_state();
+
+  nc = compile_rpn("32x9*5/+");
+  nf = compile_rpn("x32-5*9/");
+  (void)jit_emit();
+  c2f = (pifi)jit_address(nc);
+  f2c = (pifi)jit_address(nf);
+
+  printf("\nC:");
+  for (i = 0; i <= 100; i += 10) printf("%3d ", i);
+  printf("\nF:");
+  for (i = 0; i <= 100; i += 10) printf("%3d ", c2f(i));
+  printf("\n");
+
+  printf("\nF:");
+  for (i = 32; i <= 212; i += 18) printf("%3d ", i);
+  printf("\nC:");
+  for (i = 32; i <= 212; i += 18) printf("%3d ", f2c(i));
+  printf("\n");
+
+  finish_jit();
+  return 0;
+}