py: Change nlr_jump to nlr_raise, to aid in debugging.

This does not affect code size or performance when debugging turned off.

To address issue #420.
diff --git a/py/obj.c b/py/obj.c
index d4eabbe..8d5467c 100644
--- a/py/obj.c
+++ b/py/obj.c
@@ -125,7 +125,7 @@
     // TODO delegate to __hash__ method if it exists
 
     } else {
-        nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "unhashable type: '%s'", mp_obj_get_type_str(o_in)));
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "unhashable type: '%s'", mp_obj_get_type_str(o_in)));
     }
 }
 
@@ -174,7 +174,7 @@
             }
         }
 
-        nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_NotImplementedError,
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_NotImplementedError,
             "Equality for '%s' and '%s' types not yet implemented", mp_obj_get_type_str(o1), mp_obj_get_type_str(o2)));
         return false;
     }
@@ -193,7 +193,7 @@
     } else if (MP_OBJ_IS_TYPE(arg, &mp_type_int)) {
         return mp_obj_int_get_checked(arg);
     } else {
-        nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "can't convert %s to int", mp_obj_get_type_str(arg)));
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "can't convert %s to int", mp_obj_get_type_str(arg)));
     }
 }
 
@@ -228,7 +228,7 @@
     } else if (MP_OBJ_IS_TYPE(arg, &mp_type_float)) {
         return mp_obj_float_get(arg);
     } else {
-        nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "can't convert %s to float", mp_obj_get_type_str(arg)));
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "can't convert %s to float", mp_obj_get_type_str(arg)));
     }
 }
 
@@ -251,7 +251,7 @@
     } else if (MP_OBJ_IS_TYPE(arg, &mp_type_complex)) {
         mp_obj_complex_get(arg, real, imag);
     } else {
-        nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "can't convert %s to complex", mp_obj_get_type_str(arg)));
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "can't convert %s to complex", mp_obj_get_type_str(arg)));
     }
 }
 #endif
@@ -262,7 +262,7 @@
     } else if (MP_OBJ_IS_TYPE(o, &mp_type_list)) {
         mp_obj_list_get(o, len, items);
     } else {
-        nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "object '%s' is not a tuple or list", mp_obj_get_type_str(o)));
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "object '%s' is not a tuple or list", mp_obj_get_type_str(o)));
     }
 }
 
@@ -275,10 +275,10 @@
             mp_obj_list_get(o, &seq_len, items);
         }
         if (seq_len != len) {
-            nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_IndexError, "requested length %d but object has length %d", len, seq_len));
+            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_IndexError, "requested length %d but object has length %d", len, seq_len));
         }
     } else {
-        nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "object '%s' is not a tuple or list", mp_obj_get_type_str(o)));
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "object '%s' is not a tuple or list", mp_obj_get_type_str(o)));
     }
 }
 
@@ -290,7 +290,7 @@
     } else if (MP_OBJ_IS_TYPE(index, &mp_type_bool)) {
         i = (index == mp_const_true ? 1 : 0);
     } else {
-        nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "%s indices must be integers, not %s", qstr_str(type->name), mp_obj_get_type_str(index)));
+        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "%s indices must be integers, not %s", qstr_str(type->name), mp_obj_get_type_str(index)));
     }
 
     if (i < 0) {
@@ -304,7 +304,7 @@
         }
     } else {
         if (i < 0 || i >= len) {
-            nlr_jump(mp_obj_new_exception_msg_varg(&mp_type_IndexError, "%s index out of range", qstr_str(type->name)));
+            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_IndexError, "%s index out of range", qstr_str(type->name)));
         }
     }
     return i;