support unsafe_ref/assign for any isbits type, including pointer-free immutable composites
add pointer_from_objref (inverse of unsafe_pointer_to_objref)
update manual for pointer_from_objref and to note limitations on unsafe_assign
Merge pull request #2515 from stevengj/unsafe_immutable

RFC: extend unsafe_assign to work for any isbits type, add pointer_from_objref
fix #2086
why did this take 2 months?
immutability: make string types immutable.
immutability: make BigInt and BigFloat immutable.

This is slightly tricky since it requires moving the finalizer to the
data array inside of each of these, rather than the object itself,
but technically, that's more correct anyway, since if by some weird
circumstance multiple BigInts shared the same data array, the
finalizer should only be called on that data once.
immutability: make ranges immutable.
immutability: make regex-related types immutable.
immutability: make Stat immutable.
immutability: make sort Orderings immutable.
Merge branch 'master' of github.com:JuliaLang/julia
fix #2517, codegen of empty immutable structs
Merge branch 'master' of github.com:JuliaLang/julia
possibly fix #2522
make comparison chains maximally short-circuiting. fixes #2467
maybe-temporarily restore the previous behavior of \\ in custom strings
this is better for regexes, so you don't need quadruple backslash.
un-breaks the regexes in path.jl.
combined with the new behavior of \", this has the nice bonus that regexes
now print even better than before. for example r"\\\"" does not get
printed correctly in v0.1.2.
Merge branch 'master' of github.com:JuliaLang/julia into jb/kwargs