DOC: Modify JointHistogramMutualInformationImageToImageMetricv4 comments.

Author: dr.tim.allman@gmail.com
Corrected comment.

Change-Id: I9115ce0a3784319db2cc417a5537f9112490ab12
DOC: Modify JointHistogramMutualInformationImageToImageMetricv4 comments.

Author: dr.tim.allman@gmail.com
Incorrect class name in doxygen comment.

Change-Id: Iabc5a51acaadd9c3a1d8468e654c0c6a15666667
Merge topic 'EditDoxygen_JointHistogramMutualInformationImageToImageMetricv4_1363190160'

d407201 DOC: Modify JointHistogramMutualInformationImageToImageMetricv4 comments.
Merge topic 'EditDoxygen_JointHistogramMutualInformationImageToImageMetricv4_1363189266'

551d338 DOC: Modify JointHistogramMutualInformationImageToImageMetricv4 comments.