generalized and more efficient cat implementation
fix incorrect mod rounding
some cleanup in datafmt

clarify docs for the is_valid_* functions
add isless(::Char, ::Char) method (required for sort), add test
clarification
Merge pull request #7600 from Jutho/jh/cat

generalised and improved cat implementation
dSFMT: use fill_array_* API instead of genrand_* API

Both APIs are not very compatible, so let's use fill_array_* functions, which
are faster but require MersenneTwister to have an additional array field.
make Julia global RNG be an instance of MersenneTwister

The state of the global RNG was previously handled by libdSFMT.
This commit allows the global RNG to benefit speed improvements resulting
from the use of fill_array_* functions (cf. previous commit).

However, scalar calls to rand() (i.e. producing one value instead of
filling an array) using the global RNG are now slower, as well as those
filling non-Float64 arrays (less than twice as slow though).
documentation for #7704
Merge pull request #8831 from simonbyrne/mod-fix2

fix incorrect mod rounding
Hopefully fix #8842, objconv dependency not right
slight reduction in the number of comparisons for quicksort
We needed to move the objconv rules to above the openblas rules

Fixes #8842
make min/max stable. fixes #8825
remove some unnecessary Char methods
fix #8851, type intersection bug in Grid.jl tests exposed by `call` overloading
Merge pull request #8832 from JuliaLang/rf/rand-fillarray

dSFMT: use fill_array_* API instead of genrand_* API
dSFMT: remove _gv_* and _genrand_* methods

They became unneeded after 06fb0a32.
Merge pull request #8848 from stevengj/sortier

slight reduction in the number of comparisons for quicksort
test case for #8825