v0.6.16

ApproxFunOrthogonalPolynomials v0.6.16

Diff since v0.6.15

Merged pull requests:

• piecewisespace vector (#205) (@jishnub)
• AbstractVector in piecewisespace jumplocation (#206) (@jishnub)
• union_rule for Piecewise (#207) (@jishnub)
• remove ApproxFunBase testing call (#208) (@jishnub)
• remove unused maybeview call (#209) (@jishnub)
• Move ContinuousSpace to ApproxFunBase (#210) (@jishnub)
• temporarily limit fftw to <v1.6 (#211) (@jishnub)
• Fix ultraspherical Integral indexing (#212) (@jishnub)
• Add Jacobi integral tests (#213) (@jishnub)