Syntactic Niceties for Indexing

[9prady9]

• Indexing an Array using Array, Seq or a combination of both
• Assignment of indexed Array from another Array or indexed Array

[9prady9]

I have tried to use std::ops::IndexMut to enable some better syntax but that doesn't seem to fit the bill because of the way how ArrayFire's C API way of handling indexing.

Moving to timeless milestone, perhaps a compiler plugin might help but I am not sure it is worth the effort at this point.

[9prady9]

Used macros #230 to enable some nice syntax for indexing - read only operations i.e. indexing on rhs of = operation done so far.