Add a few missing prepare_* calls (needed when building for MCJTI)
remove special-case lowering for `for i = a:b` loops (ref #5355)

this fixes some edge-case loops that the special lowering did not
handle correctly.

colon() now checks for overflow in computing the length, which avoids
some buggy Range1s that used to be possible.

this required some changes to make sure Range1 is fast enough:
specialized start, done, next, and a hack to avoid one of the checks and
allow better inlining.

in general performance is about the same, but a few cases are actually
faster, since Range1 is now faster (comprehensions used Range1 instead
of the special-case lowering, for example). also, more loops should be
vectorizable when the appropriate LLVM passes are enabled. all that
plus better correctness and a simpler front-end, and I'm sold.
Merge branch 'master' of github.com:JuliaLang/julia
Fix #5435
Travis tests with release and nightly
Merge pull request #5419 from ivarne/dict-k-v

Changed Dict(ks,vs) to behave like Dict(zip(ks,vs))
Fix a few typos on windows
Windows: update download links
Incorrect link in 64e69bc
spzeros now requires both, rows and columns.

Fix #5436
when no delimiter is specified, delimiters are taken as one or more adjoining whitespaces.
fixed bug in handling empty columns.
updated tests and docs.
fixes #5391
Deprecate symmetrize! in favor of copytri!
Add pivoting to LU decomposition.
fix #5437
Improved implementation of random number generation within a range
Merge pull request #5425 from tknopp/JULIA_LOAD_PATH

Extend LOAD_PATH via environment variable
Speed up u-/l-cfirst for UTF8
Merge pull request #5427 from JuliaLang/anj/symmetrize

Deprecate symmetrize! in favor of copytri!
Merge pull request #5430 from JuliaLang/anj/lup

Add pivoting to LU decomposition.
Make u-/l-cfirst handle empty strings