Replace formula used to calculate shear LCSs
Update double gyre and Bickley jet demos to use new shear LCS formula
Merge branch 'master' into lambda_lines
Merge branch 'master' into lambda_lines
Merge branch 'master' into lambda_lines
Fix handling of NaN values in seed_curves_from_lambda_max

Algorithm to find local maximums fixed so NaNs are not classified as
local maximums.
Update ocean dataset demo to use new shear LCS formula