Rename isintegerpoly to isintegral

as mentioned in
#259 (comment)

Author: singularitti

src/common.jl

@@ -16,7 +16,7 @@ export fromroots,
        integrate,
        derivative,
        variable,
-       isintegerpoly
+       isintegral
 
 """
     fromroots(::AbstractVector{<:Number}; var=:x)
@@ -324,11 +324,11 @@ See also: [`isreal`](@ref)
 Base.real(p::AbstractPolynomial) = as_(real, p)
 
 """
-    isintegerpoly(p::AbstractPolynomial)
+    isintegral(p::AbstractPolynomial)
 
 Determine whether a polynomial is an integer polynomial, i.e., having only integers as coefficients.
 """
-isintegerpoly(p::AbstractPolynomial) = is_(isinteger, p)
+isintegral(p::AbstractPolynomial) = is_(isinteger, p)
 
 """
     coeffs(::AbstractPolynomial)

test/Poly.jl

@@ -432,11 +432,11 @@ fit(Poly, xx,yy,2)
     @test real(y) == real(x)
 end
 
-@testset "`isintegerpoly`" begin
+@testset "`isintegral`" begin
     x = Polynomial([1 // 1, Int8(2) + 0im, 3.0, Int16(4) + 0im])
     y = Polynomial([1 // 2, Int8(2) + 0im, 3.0, Int16(4) + 0im])
-    @test isintegerpoly(x) === true
-    @test isintegerpoly(y) === false
+    @test isintegral(x) === true
+    @test isintegral(y) === false
     @test convert(Polynomial{Int}, x) == Polynomial([1, 2, 3, 4])
     @test_throws InexactError convert(Polynomial{Int}, y)
 end