Window and cocoa NSWindow types

VCL's Window type and Cocoa's NSWindow type are quite different.
Naming variables as if they were the same introduces gratuitous
complexity especially when debugging stacks where both types are used.
The names of NSView type variables have been adjusted too.

(cherry picked from commit 5e6120c2)

Conflicts:
	vcl/aqua/source/app/vclnsapp.mm
	vcl/aqua/source/gdi/salgdi.cxx
	vcl/aqua/source/gdi/salgdiutils.cxx
	vcl/aqua/source/window/salframe.cxx
	vcl/aqua/source/window/salobj.cxx
	vcl/inc/vcl/sysdata.hxx
	vcl/source/window/syschild.cxx
	vcl/source/window/window.cxx

Change-Id: Ic4143dfddfa9502a529c871ac4ce0bea413b6ce9