Update INSTALL instructions

Installation instructions need to be updated, to properly list the project's dependencies and to include the new things we've introduced or changed with the cmake build.

I've made some changes, including the dependencies.

@cyberfuzzie, if you could maybe add some more details about the cmake options (`-i` and some other which might commonly be used), that would be great.
You can post them here and i'll insert them, or make commits and create a PR to my own repo, so those commits will then be included here.
(If you want to make commits, please let me know so i can hold off any changest to master; this prevents and rebasing-ugliness that could otherwise ensue)