LSliced and SLSliced Broadcasting

[ChrisRackauckas]

These were relying on the LArray broadcasts, but these now fail because of the proper index handling that was required for things like x .* x' to work. Instead, these need their own broadcast overloads so that way they can produce the correct output types, and then it should all automatically work.

[ChrisRackauckas]

@rafaqz does the multidimensional forms of #61 work for LSliced and SLSliced use cases you had? I think we might want to narrow it down to this type, and maybe give it an alternative macro for versions that are views to rows, but I think this structure might be much simpler to maintain and work with.

[rafaqz]

have to apologise here, I'm a few weeks out from handing in my thesis I might not be able to look at this for a while.