Support (T/T) \ f for expansions

[dlfivefifty]

At the moment we do expansions as

T * (T \ f)

but it might be convenient to allow an expansion operator. This would obviously be T/T, which is short-hand for T*inv(T). So the above could be changed to

(T/T)\f

I'm surprised it doesn't work already but probably just need to make sure things are flagged as lazy:

julia> Z / Z
ERROR: MethodError: no method matching similar(::Type{Array{Float64, N} where N}, ::Tuple{QuasiArrays.Inclusion{SVector{2, Float64}, DomainSets.FixedUnitBall{SVector{2, Float64}, :closed}}, QuasiArrays.Inclusion{SVector{2, Float64}, DomainSets.FixedUnitBall{SVector{2, Float64}, :closed}}})
Closest candidates are:
  similar(::QuasiArrays.AbstractQuasiArray{T, N} where N, ::Tuple) where T at /Users/sheehanolver/.julia/packages/QuasiArrays/Eszna/src/abstractquasiarray.jl:295
  similar(::AbstractBlockArray{T, N} where N, ::Tuple) where T at /Users/sheehanolver/.julia/packages/BlockArrays/g01fJ/src/abstractblockarray.jl:38
  similar(::AbstractArray{T, N} where N, ::Tuple) where T at abstractarray.jl:734
  ...
Stacktrace:
 [1] similar(A::ArrayLayouts.Rdiv{ContinuumArrays.BasisLayout, ContinuumArrays.BasisLayout, Zernike{Float64}, Zernike{Float64}}, #unused#::Type{Float64}, axes::Tuple{QuasiArrays.Inclusion{SVector{2, Float64}, DomainSets.FixedUnitBall{SVector{2, Float64}, :closed}}, QuasiArrays.Inclusion{SVector{2, Float64}, DomainSets.FixedUnitBall{SVector{2, Float64}, :closed}}})
   @ ArrayLayouts ~/.julia/packages/ArrayLayouts/75WvP/src/ldiv.jl:17
 [2] similar(A::ArrayLayouts.Rdiv{ContinuumArrays.BasisLayout, ContinuumArrays.BasisLayout, Zernike{Float64}, Zernike{Float64}}, #unused#::Type{Float64})
   @ ArrayLayouts ~/.julia/packages/ArrayLayouts/75WvP/src/ldiv.jl:18
 [3] similar(A::ArrayLayouts.Rdiv{ContinuumArrays.BasisLayout, ContinuumArrays.BasisLayout, Zernike{Float64}, Zernike{Float64}})
   @ ArrayLayouts ~/.julia/packages/ArrayLayouts/75WvP/src/ldiv.jl:19
 [4] copy
   @ ~/.julia/packages/ArrayLayouts/75WvP/src/ldiv.jl:21 [inlined]
 [5] materialize
   @ ~/.julia/packages/ArrayLayouts/75WvP/src/ldiv.jl:22 [inlined]
 [6] rdiv
   @ ~/.julia/packages/ArrayLayouts/75WvP/src/ldiv.jl:87 [inlined]
 [7] /(A::Zernike{Float64}, B::Zernike{Float64})
   @ QuasiArrays ~/.julia/packages/QuasiArrays/Eszna/src/matmul.jl:38
 [8] top-level scope
   @ REPL[32]:1

[dlfivefifty]

Done. In fact T/T\f works.