biff rewrite: _f -> _va, plus using AIR_CALLOC, plus implementation of stackblur functions changed
biff rewrite: _f -> _va, plus using AIR_CALLOC, plus implementation of stackblur functions changed

git-svn-id: 9e9401559e51101c165cdce4d49b411eb20436ed@4364 3d70eeeb-363e-0410-a505-8a46323a89f2

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