Remove the interp() wrapper

As it is equivalent to simply call spline3() directly.
Use eps for comparisons

Fixes #9
Merge pull request #11 from certik/spline_fix

Spline fix
Merge pull request #13 from aeberspaecher/linalg

Call stop_error() instead of using the stop statement
Add .travis.yml file
Use forall statement instead a loop in eye().
Merge branch 'master' into linalg
Prefer use of size(A, 1) over size(A(:,1))