Allow prefetching of a range of mapped file

[CAFxX]

This is an attempt at implementing #65. The PR is currently untested because I've been unable to build larray locally, so hopefully travis will be able to do it.

[CAFxX]

Seems like travis is not rebuilding the native libraries

[CAFxX]

@xerial I'm unable to get make all to work (tried both on Ubuntu and Mac OS), and I can't find instructions on how to set up the build env to be able to build the native libraries. Do you have a VM or container image that I can use? Alternatively, can you build the libraries and update the PR?

[xerial]

@CAFxX Thanks for the update. I’m thinking about using docker images for supporting building binary images on Travis CI so that you don’t need to set up native compiler on your machine.

I did the same approach in sqlite-jdbc project, and it has been working well. I just need to migrate some scripts from this to here.

[CAFxX]

@xerial that would be great. Please let me know once it's ready; unfortunately, it feels like there's not much I can do until then...

[CAFxX]

@xerial any update?

[xerial]

@CAFxX Sorry about the delay. I still don't have sufficient time to work on this.

[CAFxX]

Should I close the PR then?

[xerial]

@CAFxX Please leave it open.