Avoid line-continuation in cshell assignment

As noted during #1667 (closed), there is an issue with BSD-csh.

The following construct looks ok, and works fine with tcsh but fails with BSD csh.

# Obtain major.minor from `paraview --version`
set pv_api=`paraview --version | \
    sed -ne 's/^[^0-9]*\([0-9][0-9]*\.[0-9][0-9]*\).*$/\1/p'`

Need to use the uglier form, without continuations

set pv_api=`paraview --version | sed -ne 's/^[^0-9]*\([0-9][0-9]*\.[0-9][0-9]*\).*$/\1/p'`

Not entirely clear why this is.

@alexey