ENH: Do not SEND_ERROR at CMake configure time when optional components are not found. Emit the message instead as a mere warning.
ENH: Do not SEND_ERROR at CMake configure time when optional components are not found. Emit the message instead as a mere warning.

git-svn-id: 9e9401559e51101c165cdce4d49b411eb20436ed@4062 3d70eeeb-363e-0410-a505-8a46323a89f2

BRAINSia/teem,BRAINSia/teem,Slicer/teem,BRAINSia/teem,Slicer/teem,Slicer/teem,BRAINSia/teem,Slicer/teem,BRAINSia/teem,Slicer/teem