Use lessc dependencies to trigger re-renders

[bhagany]

It turns out that lessc has a relatively easy way of tracking dependencies for the files that it compiles, and we can leverage this to know when to recompile at a granular level. There are no user-facing api changes.

[arichiardi]

@bhagany first of all thanks as usual for working on this.

The patch achieves reloading of imported files, like .variables and .overrides for Semantic UI.
There is a problem though: at the end of the pipeline I see the following and the main css file does not seem to be updated:

Process completed successfully.
[lessc] - copied unchanged file public/css/blog.css
Sifting output files...

[arichiardi]

This still has the problem described, seems like a simple fix, will do my best to check that

[allentiak]

(Just explicitly mentioning previous comments...)

The patch achieves reloading of imported files, like .variables and .overrides for Semantic UI.
There is a problem though: at the end of the pipeline I see the following and the main css file does not seem to be updated:

Process completed successfully.
[lessc] - copied unchanged file public/css/blog.css
Sifting output files...

[arichiardi]

Will have to check this, after one year I forgot about it and of course it is a very nice to have 😀