fix bounds bug in getindex(a:b, c:d) with c<1

And more laconic Julia.

Commit 646fe6b3 eliminated a non "redundant bounds check", which is here
re-introduced via `check_indexingrange` function.
fall back on apropos if help fails; partially fixes #8262
fix #8338, syntax bug in 1-line function def with keyword args
Merge branch 'master' of github.com:JuliaLang/julia
check indices in sparsevec(::Dict). fixes #8363
Merge pull request #8373 from tanmaykm/fix8363

check indices in sparsevec(::Dict). fixes #8363
Merge pull request #8351 from rfourquet/range-getindex

fix bounds bug in getindex(a:b, c:d) with c<1
membuf is now a std::unique_ptr in llvm3.6
Merge pull request #8327 from davidssmith/help

fall back on apropos() if help() fails; fixes #8262
Merge pull request #8374 from jakebolewski/jcb/fixllvm36osx

llvm-3.6 getMemBuffer now returns a std::unique_ptr<MemoryBuffer>