Always use 'this' handle when applicable.

Change-Id: I953544d8d550d45645cb7c1cd4bf220c27ed58ab
By default, hyper tree grid source will use dual grid API

Change-Id: I8b00f594f5a6c3222f40af247a28b116001c6755
It is no longer necessary for tests to specify which grid to use

Change-Id: Ide2a7e8dbe08a586af6711d71a350a0f4ffa1a62
A number of fixes

Re-formatted recent changes that were not exactly VTK-compliant.
Also removed forced re-setting of dual grid iVar

Change-Id: Ia78727270ff3c2d60658ec5cba1c3d64579c8425
Eliminated all references to Dual grid setting from HTG source

Change-Id: I2ad4fb0bf4e81ece49be14661cd2e28582c4621c
Removed entirely the primal grid API

Change-Id: I506a894e29760ca22581bdf60c5d6a7d68473fb5
Eliminated all references to dual grid in primal filters

NB: This also allows for some performance optimization as the
duality of Cell and Point arrays is handled at once at
initialization only.

Change-Id: I55b5a8baca2130ac733e12b3dddf95eba1ae4520
Eliminated UseDualGrid instance variable and ancillary methods.

Change-Id: I99efbd0df52295f967b3fe67ebb424f1ee860554
Merge topic 'eliminate_primal_grid_from_hypertreegrid_API' into master

9c058159 Eliminated UseDualGrid instance variable and ancillary methods.
e4981db0 Eliminated all references to dual grid in primal filters
08119bab Removed entirely the primal grid API
239a63ea Eliminated all references to Dual grid setting from HTG source
a08374bf A number of fixes
1d5b289e It is no longer necessary for tests to specify which grid to use
911b45a2 By default, hyper tree grid source will use dual grid API
45eb44a7 Always use 'this' handle when applicable.