Merge pull request #15 from yumin/master

entity-vis-color controls
Merge pull request #16 from yumin/master

Fixed a couple issues with parsing set-property op result
Merge pull request #17 from yumin/master

The summary phrases should be visible by default
Merge pull request #18 from yumin/master

Added signal to notify data changed in modelView
Don't force the instantiators on
Use the VTK_RENDERING_BACKEND variable for deps

This makes it easy to switch between OpenGL legacy, and the new
OpenGL backend without hardwiring one or the other. It does require
a recent enough VTK that this variable is set/exposed in the Config.
Merge pull request #19 from cryos/opengl2-build-updates

Opengl2 build updates
Maintain compatibility with older VTK/ParaView

The VTK_RENDERING_BACKEND variable was not always exposed in the VTK
config file, define it to OpenGL if it is not defined.
Merge pull request #20 from cryos/opengl2-build-updates

Maintain compatibility with older VTK/ParaView