BUG: Verify ConfidenceConnected Seeds

Seeds outside image were resulting in segfaults. Now, seeds are
verified that they are inside the region, and if there are no valid
seeds a zero image is return consistent with the other region growing
algorithms.

Change-Id: Idcbf4deda92f417b216ced6fb79c5dc6fbf39c58
BUG: Verify seeds in VectorConfidenceConnected

Prevent segfault from invalid access. Only use valid seeds inside
region, return 0 image if there are no valid seeds. This behavior is
the same as other region growing algorithms.

Change-Id: I3f9d1525d1079502cbf9f44be47f02d385c9c15b
Merge topic 'ConfidenceConnectedSeedValidate'

18416bb BUG: Verify seeds in VectorConfidenceConnected
9225cb1 BUG: Verify ConfidenceConnected Seeds