a little spring cleaning to remove some compiler warnings for

implicit declarations, redundant redeclarations, missing initializers,
nested externs and other cruft.

Cleaned up includes and moved extern _Type decls from Types.h into
Types.c since that is the only place where they are needed now.

Did not touch Ipo.[ch] since work is on-going there.

source/blender/python/api2_2x/vector.h

@@ -35,6 +35,8 @@
 
 #include <Python.h>
 
+extern PyTypeObject vector_Type;
+
 #define VectorObject_Check(v) ((v)->ob_type == &vector_Type)
 
 typedef struct {