macros for turning off bounds checks. fixes #1392

`@inbounds expr` allows bounds checks to be omitted for code syntactically
inside the argument expression.

adds @inbounds to matmul, comprehensions, and vectorized binary operators.
Merge branch 'master' of github.com:JuliaLang/julia into jb/inbounds
Merge branch 'master' of github.com:JuliaLang/julia into jb/inbounds
clarify boundscheck expressions
Merge branch 'master' of github.com:JuliaLang/julia into jb/inbounds
Merge branch 'master' of github.com:JuliaLang/julia into jb/inbounds

Conflicts:
	src/alloc.c
	src/codegen.cpp
	src/jltypes.c
Support mmap on Windows
Don't export munmap
Small fixes discovered by testing on binary
optimize ... when delegating an arglist. ref #3440
Merge branch 'master' of github.com:JuliaLang/julia
avoid redundant re-loads out of GC frame. ref #3440
happens to make sparse mul faster; #942
Merge branch 'master' of github.com:JuliaLang/julia
cleanup some windows errata
Pkg2: an installed package is any directory besides METADATA and .*
Merge branch 'master' of github.com:JuliaLang/julia
Merge branch 'master' of github.com:JuliaLang/julia
fix perf regression in calls to jl_array_ptr
Pkg2: slight error/info messaging tweak.
fix #2915, BigInt memory leak