* Bug: In ClockTree plugin, only the logical view of the clock buffer
was loaded, so no external components where found on the I/O nets.
The external components are loaded only when the *physical* view
is loaded. Didn't show on sxlib because the buffer was fulled
loaded *before* running the ClockTree.
* Bug: In PyHurricane, in the various LocatorNextMethod() macros,
sometimes an empty collection can be returned by Hurricane
(GenericCollection()), which has a NULL locator. So check
if the locator is *not* NULL before trying to access it...
* Change: In Chip, more accurate error messages related to the clock
detecttion.
e6c809a12a