Deprecate use of SelectSegBinaryLayer

[williford]

Create examples with using multiple inputs, without relying on SelectSegBinaryLayer and encourage the use of this layer.

BVLC#4850

[williford]

In order to replace the functionality of SelectSegBinaryLayer (around line 339 in the cpp file), it would be helpful to have a "Lookup layer", that uses a lookup vector (most likely a one-hot encoded vector) to convert the labels of a segmentation map (for example, 10 labels of PASCAL VOC into either Foreground or Background, depending on which segmentation classes are currently "active").