ArrayViews

[Dahua]

Some of you may have noticed that I recently released an ArrayViews package: https://github.com/lindahua/ArrayViews.jl

Here are the main features (copied from the readme):

• An efficient view function that implements array views
• Support of arrays of arbitrary dimension and arbitrary combinations of indexers
• Support view composition (i.e. construct views over views)
• Special attention to ensure type stability in most cases
• Efficient indexing (both cartesian and linear)
• Light weight view construction
• A systematic approach to detect contiguous views (statically)
• Views work with linear algebra functions

I am also making a PR at #5556 to push this to the Julia Base. Given that the PR is large, it may take a while to review. In the mean-time, please checkout the package.

Related to this, I modified NumericExtensions.jl, which is now tagged 0.4.0, and deprecate the ``unsafe_view`` function. I replaced all the use of ``unsafe_view`` in this package with a much safer version ``view`` and sees no obvious performance regression in my benchmarks. This indicates that the array view system should be efficient enough for general use.