Build: Skip steps

[zalito12]

Body

Summary

Add flags to cli to allow skip steps on build process.

Background & Motivation

We all know that the build process is the bottlekneck of the Astro awesomeness, the incremental build to allow build just one single page/route/document will be the icing on the cake, but what about when you change just one small detail of your project, why do every build step.

I was building my first project and I changed a small detail on the template of a long collection, but the images and their sizes didn't change, I would like to skip the image optimization step.

Goals

• Make re-builds faster
• Skip image optimization on build

Example

Add some kind of flag to skip image optimization like "--skip-images".
I don't know how build works, but I guess it would involve some kind of cache to keep track of the already existing images hashes on the html generation.

[Princesseuh]

Images are already cached between builds

[zalito12]

Wow, That's awesome, as I said I don't too much about the background working of the build process, my apologies.