Add option to clean css before template compile

[phun-ky]

Greatly reduces size of styles (I shaved over 3 megabytes per page in my use case) :)

This uses clean-css to remove dupes. But sadly, it is a bit slow, and has to be run for every page you make. For my sake, it's doing the same job 4 times, with the same css, since I have 4 pages. But the gains outweighs the pain here, for now

(This is a new PR, the old one (#21 ) was based on an old version of gulp-livingcss)

[phun-ky]

gulp 1,60s user 0,20s system 132% cpu 1,363 total

vs

gulp 45,34s user 0,40s system 104% cpu 43,971 total

This is on ubuntu, which is ordinarily fast :S

[phun-ky]

Updating this pr with only level 1 + dedupe, since that was our main goal, and it's faster:

gulp 6,89s user 0,40s system 115% cpu 6,309 total

[straker]

Thanks for the the pr. A few questions for my understanding:

• html-minifier uses clean-css for the minifyCSS parameter, any reason why we don't use that instead?
• I'v actually been thinking of removing the html-minifier option since it's something that could be done in the next step of a gulp process if you wanted to. Then the user could set all the options. e.g.

gulp.src('styles/**')
  .pipe(livingcss('dest'))
  .pipe(htmlMinifer(options))
  .pipe(gulp.dest('dest'))

Does piping the output of livingcss into clean-css not work?

• Since the parsedStylesheets are taken from the styles piped into livingcss, could you concat and dedup them before passing them into livingcss? Then you'd only have to do it once no matter how many pages there are

[phun-ky]

Yikes! Did not realize that that was an option! Updated the PR now. If users want to minifyCSS and want to provide their own config, you can do this now :):

  livingcss('bin', {
    template: './template/template.hbs',
    sortOrder: ['introduction', 'foundation', 'guidelines', 'resources'],
    minifyCSS: {
      level: {
        2: {
          all: false, // sets all values to `false`
          removeDuplicateRules: true // turns on removing duplicate rules
        }
      }
    },
    minify: true,

[straker]

Awesome!