Generalize `blockisequal` to arrays, introduce `blockequals` and `blockisapprox`#477

dlfivefifty merged 3 commits intoJuliaArrays:masterJuliaArrays/BlockArrays.jl:masterfrom

mtfishman:mf/generalize_blockisequalmtfishman/BlockArrays.jl:mf/generalize_blockisequalCopy head branch name to clipboard