2.5 Python

Merging changes made by Arystanbek in the soc-2009-kazanbas branch,
plus some things modified and added by me.

* Operator exec is called execute in python now, due to conflicts
  with python exec keyword.
* Operator invoke/execute now get context argument.
* Fix crash executing operators due to bpy_import_main_set not being
  set with Main pointer.
* The bpy.props module now has the FloatProperty/IntProperty/
  StringProperty/BoolProperty functions to define RNA properties for
  operators.
* Operators now have an __operator__ property to get the actual RNA
  operator pointers, this is only temporary though.
* bpy.ops.add now allows the operator to be already registered, it
  will simply overwrite the existing one.
* Both the ui and io directories are now scanned and run on startup.

source/blender/python/intern/bpy_util.c

@@ -81,6 +81,7 @@ int BPY_flag_from_seq(BPY_flag_def *flagdef, PyObject *seq, int *flag)
 	char *cstring;
 	PyObject *item;
 	BPY_flag_def *fd;
+	*flag = 0;
 
 	if (PySequence_Check(seq)) {
 		i= PySequence_Length(seq);
@@ -108,6 +109,9 @@ int BPY_flag_from_seq(BPY_flag_def *flagdef, PyObject *seq, int *flag)
 		error_val= 1;
 	}
 
+	if (*flag == 0)
+		error_val = 1;
+
 	if (error_val) {
 		char *buf = bpy_flag_error_str(flagdef);
 		PyErr_SetString(PyExc_AttributeError, buf);