Improve error reporting in Multipole

[Ian Hinder]

When Multipole encounters an interpolation error, the error output from the interpolator consists of thousands of lines each listing the points that failed. This is too much information to process. It is also not clear that the error came from Multipole.

1. This output should be limited; 2. The error should be prefixed with "Multipole" so the user knows which thorn was responsible for calling the interpolator (maybe the new CCTK_ScheduleQueryCurrentFunction from #817 could be used for this); 3. Multipole should contain a check in CCTK_PARAMCHECK that the extraction radii are not outside the Cactus base grid.

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