Fix: rename _placeHolderView and add accessors in CPTabView.j (#2678)
Fix: rename _placeHolderView and add accessors in CPTabView.j (#2678)

In CPTabView.j on line 706 method is called `[_source
_setPlaceholderView:aValue]; ` this method does not exist, and this
call could possibly be expecting the property `_placeHolderView` to
have an accessor method. To add the correct accessor method the case of
either the method call selector or the variable must change —
`_placeHolderView` vs `_placeholderView`. For this fix I selected the
`_placeholderView` spelling, as opposed to the alternative with the
capitalized “holder” in “placeholder.”

Fixes #2674
daboe01/cappuccino,enquora/cappuccino,cappuccino/cappuccino,enquora/cappuccino,daboe01/cappuccino,Rosch/cappuccino,cappuccino/cappuccino,daboe01/cappuccino,daboe01/cappuccino,enquora/cappuccino,Rosch/cappuccino,Rosch/cappuccino,Rosch/cappuccino,Rosch/cappuccino,enquora/cappuccino,enquora/cappuccino,cappuccino/cappuccino,cappuccino/cappuccino,cappuccino/cappuccino,cappuccino/cappuccino,cappuccino/cappuccino,daboe01/cappuccino,enquora/cappuccino,daboe01/cappuccino,enquora/cappuccino,Rosch/cappuccino,Rosch/cappuccino,daboe01/cappuccino