improve performance of vcat and hcat of numbers of different types

helps #4467
try to fix #4478
simplify implementation of os test macros
fix #3486

since size(a,d) supports d > ndims(a), this should be allowed in general
Pkg: make release-0.2 the current METADATA branch.
Pkg: reconsidered coupling versioning of Julia with metadata formats.
Pkg: rename Entry._resolve => Entry.resolve
ordering: deprecate the `order` keyword for ordering-related functions.
test/sorting.jl: remove usages of `order` keyword.
fix #4486
Complete fix #4478
Fix pisum and mandelbrot microbenchmarks
Merge pull request #4490 from magistere/ys/micro

Fix pisum and mandelbrot microbenchmarks
Merge pull request #4489 from magistere/master

Complete fix #4478
fix #4482
Added eltype(::String) fixes #4491
add test for #4486
Merge pull request #4493 from ivarne/eltype_string

Added eltype(::String) fixes #4491
add another eltype definition for String
fix #4487