remove deprecations

[joshday]

Removing deprecations that have been around for a year and many releases

[piever]

Could you also add IndexedTable as a synonym for NextTable (I think that was the original plan)? Or you think this should be done in a future PR?

[joshday]

Do you have a link to a conversation somewhere? The idea is to rename NextTable to IndexedTable?

One of the lines this PR removes is

Base.@deprecate_binding IndexedTable NDSparse

although IndexedTable isn't exported.

[piever]

IndexedTable used to be what is now NDSparse and it was the only table type offered here. Then @shashi had the idea to create a table where some columns are sorted and to call this IndexedTable instead. However, not to subtly change meaning of the word, IndexedTable was deprecated and the thing was called NextTable instead. Now it's probably a safe time to bring IndexedTable back to the intended meaning. The design of the API is discussed in JuliaData/JuliaDB.jl#80 and implemented in #85

[joshday]

Thanks for the links! Since this is ready to go I'm going to merge it, but that will be next on my list of things to do.