Make MersenneTwister equivalent in 32- and 64-bit architectures

As mentioned in issue #5999, reproduce the solution in 67f6fee for the MersenneTwister.

Note that users on 64-bit architectures will see their randomness change with no change in their seed.
fix #6033 and #6044

- trap errors inside timer callbacks
- protect timers from GC
- ignore uv alloc requests when handle->data==NULL
Fix julia lu algorithm to handle singular matrices similarly to LAPACK.
Pg 7: "UInt" - "Uint"

"UInt" is not the correct name; it should be "Uint"
Merge pull request #6067 from gajjanag/patch-1

Pg 7: "UInt" - "Uint"
move resetstkoflw to start of catch block in interpreter
Base.Printf: get rid of unnecessary leading underscores in names.

This was briefly the way to indicate that a name was private to a
module, but we no longer do things that way.
BigFloat printf: prevent assertion errors [#5756].

Now you get stack overflow or no method errors instead, which at
least doesn't kill the process, so that's an improvement. The real
solution is to implement decoding for BigFloat and BigInt (coming).
fix #6052
Merge branch 'master' of https://github.com/JuliaLang/julia
formatting fixes
Merge branch 'master' of https://github.com/JuliaLang/julia into jb/uvfixes
tolerate multiple calls to stop_timer
remove IdleAsyncWork, add_idle_cb, queueAsync
base/gmp.jl: define string(::BigInt) = dec(x).

The definition that used gmp_snprintf is ancient and unnecessary.
Merge pull request #6049 from JuliaLang/jb/uvfixes

fix #6033 and #6044
base/printf.jl: use `a in b` syntax instead of `in(a,b)` syntax.
recognize ARCH=i586 in openblas config in deps/Makefile. ref #6029
Merge pull request #6018 from jperla/newtwist

RFC: Make MersenneTwister equivalent in 32- and 64-bit architectures
base/grisu.jl: use zero-dimensional arrays for NEG, LEN & POINT.

Since zero-dimensional arrays always have size 1, this might avoid
some bounds checks that otherwise have to be done.