Manage => Pages may produce orphaned page

[hailin]

because array_splice may not preserve the original numeric index, it causes our pages display to produce orphaned pages.

[hailin]

In most cases, array_splice preserves index, yet, by spec, it may not.
When it doesn't, that is causing problems.
To fix this, we set $i to -1, thus when ++ed, it starts from 0.

[hailin]

patch

[ryan]

(In [6427]) Orphaned page fix from hailin. fixes #5498

[hailin]

patch walk class to make similar index change.
It is in 5498_pages_2.diff

[hailin]

fix bad pages whose parent = itself

[hailin]

I've put all three fix together. All three should go into wporg as each fixes one different issue.

[hailin]

make the behavior completely the same as the original walk class

[ryan]

(In [6456]) Page walker fixes from hailin. fixes #5498

[ryan]

Some extra stuff got in there. Reverted with [6457].