bug#41408: Add a project-compile command

[Dmitry Gutov]

Hey Philip,

On 19.05.2020 21:24, Philip K. wrote:
> this patch adds a `compile' command for project.el. It's nothing fancy,
> just sets the first directory of `project-roots' as `default-directory',
> and then calls the regular compile.
>
> The TODOs mention a `project-build' command, and from my interpretation,
> this is a slimmed down version (hence the other name, but also because
> it just called compile in a different environment).

Is this a command you'd be using yourself? If so, we'll add it happily.

I'm just asking because it's indeed bare-bones, and I basically never 
use 'M-x compile' directly.