documented object constrs; endb works again

examples/debugging.nim

@@ -0,0 +1,17 @@
+# Simple program to test the debugger
+# compile with --debugger:on
+
+proc someComp(x, y: int): int =
+  let a = x+y
+  if a > 7:
+    let b = a*90
+    {.breakpoint.}
+    result = b
+  {.breakpoint.}
+
+proc pp() =
+  var aa = 45
+  var bb = "abcdef"
+  echo someComp(23, 45)
+
+pp()