accept numbers as integral orders (#223)

Author: jishnub

src/Spaces/IntervalSpace.jl

@@ -8,4 +8,7 @@ Fun(::typeof(identity), d::IntervalOrSegment{<:Number}) =
     Fun(Chebyshev(d), [mean(d), complexlength(d)/2])
 
 # the default domain space is higher to avoid negative ultraspherical spaces
-Integral(d::IntervalOrSegment,n::Integer) = Integral(Ultraspherical(1,d), n)
+function Integral(d::IntervalOrSegment, n::Number)
+    assert_integer(n)
+    Integral(Ultraspherical(1,d), n)
+end

src/Spaces/Ultraspherical/UltrasphericalOperators.jl

@@ -314,7 +314,8 @@ end
 
 
 # TODO: include in getindex to speed up
-function Integral(sp::Chebyshev{DD},m::Integer) where {DD<:IntervalOrSegment}
+function Integral(sp::Chebyshev{DD}, m::Number) where {DD<:IntervalOrSegment}
+    assert_integer(m)
     usp = Ultraspherical(m,domain(sp))
     I = Integral(usp,m)
     C = Conversion(sp,usp)