v2.1.0

• A 5-argument version for mul!(y, A::LinearMap, x, α=1, β=0), which computes y := α * A * x + β * y and implements the usual 3-argument mul!(y, A, x) for the default α and β.
• Synonymous convert(Matrix, A::LinearMap) and convert(Array, A::LinearMap) functions, that call the Matrix constructor and return the matrix representation of A.
• Multiplication with matrices, interpreted as a block row vector of vectors:
  • mul!(Y::AbstractArray, A::LinearMap, X::AbstractArray, α=1, β=0): applies A to each column of X and stores the result in-place in the corresponding column of Y;
  • for the out-of-place multiplication, the approach is to compute convert(Matrix, A * X); this is equivalent to applying A to each column of X. In generic code which handles both A::AbstractMatrix and A::LinearMap, the additional call to convert is a noop when A is a matrix.
• Full compatibility with Arpack.jl's eigs and svds.