fixing -Wconversion warnings, leading to fix of _nrrdKeyValueIdxFind being public (now its static _kvpIdxFind) and returning the wrong type. Also cleaned up representation of not finding a given key, with explicit found/not-found indicator
fixing -Wconversion warnings, leading to fix of _nrrdKeyValueIdxFind being public (now its static _kvpIdxFind) and returning the wrong type. Also cleaned up representation of not finding a given key, with explicit found/not-found indicator

git-svn-id: 9e9401559e51101c165cdce4d49b411eb20436ed@5629 3d70eeeb-363e-0410-a505-8a46323a89f2

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