Add support for NumPy insert

[stuartarchibald]

Feature request

As title. From https://gitter.im/numba/numba?at=5c8f2a2da21ce51a207b2899.

[shimst3r]

Hey @stuartarchibald, I'd like to work on this issue. 😄

Given that I'm fairly new to the numba code base, where exactly is NumPy support implemented? I've found the np directory, but to be honest I'm not sure how to navigate the modules properly.

/Edit: Looking further, I found arrayobj.np_append, so I guess this is the correct place for np_insert?

[stuartarchibald]

@shimst3r great, thanks for taking it up. Yes, you are right about the location.

The use of Numba's extension API @overload decorator is strongly recommended for this task. A guide to using @overload is here and API documentation is here.

It may be useful to take a look at examples of pull requests adding support for a NumPy function that have already been done if guidance is needed... here's a couple:

• np.roll: https://github.com/numba/numba/pull/3563/files
• np.roots: https://github.com/numba/numba/pull/2135/files

As a new contributor, some instructions for getting set up for development are here and are a great place to start.

If you get stuck/need a hand, the Numba core developers are also available on gitter.im real time chat.