bugs in facm()

[githubtomtom]

calling fit(FactorAnalysis, x) sometimes would get:

ERROR: DomainError with -0.9999999999999778:
sqrt will only return a complex result if called with a complex argument. Try sqrt(Complex(x)).
Stacktrace:
 [1] throw_complex_domainerror(f::Symbol, x::Float64)
   @ Base.Math ./math.jl:33
 [2] sqrt(x::Float64)
   @ Base.Math ./math.jl:582
 [3] facm(S::Matrix{Float64}, mv::Vector{Float64}, n::Int64; maxoutdim::Int64, tol::Float64, η::Float64, maxiter::Int64)
   @ MultivariateStats ~/.julia/packages/MultivariateStats/HTpHt/src/fa.jl:119
 [4] fit(::Type{MultivariateStats.FactorAnalysis}, X::Matrix{Float64}; method::Symbol, maxoutdim::Int64, mean::Int64, tol::Float64, η::Float64, maxiter::Int64)
   @ MultivariateStats ~/.julia/packages/MultivariateStats/HTpHt/src/fa.jl:173

which should be caused by:

        q′ = λ[q] > 0 ? q : findlast(λ .> 0)

        λq = 0.0
        @inbounds for i in 1:q′
            λq += log(λ[i]) - λ[i] + 1.
            V[i] = sqrt(λ[i] - 1.)         # <---  λ is guaranteed to be > 0, but NOT >= 1
        end

inside facm(). In fact, the λ can be smaller than 1, and an error would be triggered.