Made Sliders a little bit wider by default.
Added numeric fields to ColorChooser.

These are in additional to the existing sliders.

Fixes #166.
Updated Changes file.
Added a ParentConstraint node to GafferScene.

Fixes #26.
Merge pull request #708 from johnhaddon/parentConstraint

Added a ParentConstraint node to GafferScene.
Merge pull request #706 from johnhaddon/colorChooserNumericFields

Color chooser numeric fields
Added a targetOffset plug to the GafferScene::Constraint node.

This is an additional translation (in target space) applied to the target transform. It is of most use for the AimConstraint node, but since it has potential uses in the other constraints, and the Constraint base class specifies everything else about the target, it seemed most reasonable to implement it in the base class.

Fixes #278.
Merge pull request #709 from johnhaddon/aimConstraintOffset

Added a targetOffset plug to the GafferScene::Constraint node.
Updated Changes file.