[Build Tools] update to gulp4

[ColinFrick]

Description

Update all dependencies with gulp 4
Admin package was updated, but was not tested

• Verify css / js / assets build process (full / incremental)
• Finish "watch" task
• Test and finish "docs" tasks
• Batch changes in "watch"
• Handle deleted files (or skip)

Closes

#112 / Semantic-Org/Semantic-UI#6549 / Semantic-Org/Semantic-UI#3793

[y0hami]

Great work @ColinFrick, I will try and get some testing done in the next few days.

[prudho]

I have tested most used commands (install, build, watch...) without getting any warning or error. I have checked code and everything looks fine.

Bonus point, Travis built the whole PR all by itself, smoothly.

This is a great job, LGTM 👍

[y0hami]

I just did some quick testing and found this error

Site folder exists, merging files (no overwrite) src/site/
[15:51:22] 'create install files' errored after 1.94 ms
[15:51:22] Error: ENOENT: no such file or directory, stat './src/_site'
    at Object.statSync (fs.js:829:3)
    at Object.exports.copyDirSyncRecursive (G:\fomantic\Fomantic-UI\node_modules\wrench-sui\lib\wrench.js:244:23)
    at G:\fomantic\Fomantic-UI\tasks\install.js:341:12
    at taskWrapper (G:\fomantic\Fomantic-UI\node_modules\undertaker\lib\set-task.js:13:15)
    at bound (domain.js:396:14)
    at runBound (domain.js:409:12)
    at asyncRunner (G:\fomantic\Fomantic-UI\node_modules\async-done\index.js:55:18)
    at process._tickCallback (internal/process/next_tick.js:61:11)
[15:51:22] 'install' errored after 2.86 s
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! fomantic-ui@2.6.2 install: `gulp install`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the fomantic-ui@2.6.2 install script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

Steps:

1. npm install then went through the installation process selecting all the default values
2. rm -rf node_modules
3. npm install this time it asked to extend my config and I selected Yes then Automatic.

[ColinFrick]

Weird because I didn’t really change install

I’ll look into it as soon as I’m home

[ColinFrick]

As I suspected this is a pre-existing problem. Just tested this on master
gulp install removes the _site directory, which other scripts are relying on.

How should we proceed with this problem? This should only affect users who clone the repository, and don't use fomantic-ui throughb npm.

[y0hami]

Is there a way to check if _site exists before running the script and then showing a friendly error instead of the script crashing?

[y0hami]

👍

[lubber-de]

LGTM
Great work! Much appreciated. 👍