support for gulp 4

[zacny]

I tried to use your plugin with gulp 4 without success. Do I missed something?
Here is my gulpfile.js
`var gulp = require('gulp'),
order = require("gulp-order"),
concat = require('gulp-concat'),
replace = require('gulp-replace-task'),
rename = require("gulp-rename"),
header = require('gulp-header'),
clean = require('gulp-clean'),
server = require( 'gulp-develop-server'),
livereload = require('gulp-livereload'),
sync = require('gulp-npm-script-sync'),
pkg = require('./package');
fs = require('fs');

var config = {
tmp_dir: 'tmp',
dist_dir: 'dist',
css_dir: 'src/css',
src_dir: 'src',
source_dir: 'src/source',
static_dir: 'src/static',
util_dir: 'src/util',
script_name: pkg.config.scriptName,
css_name: pkg.config.cssName,
server: {
options: {
path: './app/server.js'
},
files: [
'./app/server.js',
pkg.config.cssName,
pkg.config.scriptName
]
},
developement: false
};

function detectDevelopmentFlag(cb){
if (process.argv.indexOf('--development') > -1) {
config.developement = true;
}
cb();
}

function cleanTmpFiles() {
return gulp.src(config.tmp_dir + "/*", {read: false}).pipe(clean());
}

function utilPartAttach() {
return gulp.src(config.util_dir + '/*.js')
.pipe(order([
'const.js', 'tool.js', 'domTamper.js', 'videoGrabber.js',
'configurator.js', 'changeVideoDetector.js', 'wrapperDetector.js'
]))
.pipe(concat('utils.js'))
.pipe(gulp.dest(config.tmp_dir));
}

function sourcePartAttach() {
return gulp.src(config.source_dir + '/*.js')
.pipe(order([
'tvp_vod.js', 'tvp_cyf.js', 'tvp_reg.js', 'tvp.js', 'tvn.js',
'ipla.js', 'vod.js', 'vod_ipla.js', 'wp.js', 'cda.js'
]))
.pipe(concat('sources.js'))
.pipe(gulp.dest(config.tmp_dir));
}

function runPartAttach() {
return gulp.src(config.src_dir + '/*.js')
.pipe(order([
'starter.js', 'attach.js'
]))
.pipe(concat('execute.js'))
.pipe(gulp.dest(config.tmp_dir));
}

function joinScriptParts() {
return gulp.src(config.tmp_dir + '/*.js')
.pipe(order([
'utils.js', 'sources.js', 'execute.js'
]))
.pipe(concat('content.js'))
.pipe(gulp.dest(config.tmp_dir));
}

function joinCssFiles(){
return gulp.src(config.css_dir + '/*.css')
.pipe(order([
'download.css', "buttons.css", "sources.css"
]))
.pipe(concat(config.css_name))
.pipe(gulp.dest(config.dist_dir));
}

function addTabulators(){
return gulp.src(config.tmp_dir + '/content.js')
.pipe(replace({
patterns: [
{//linux
match: /(?:\n)/g,
replacement: '\n\t'
},
{//windows
match: /(?:\r\n)/g,
replacement: '\r\n\t'
}
]
}))
.pipe(gulp.dest(config.tmp_dir))
}

function fillTemplate() {
return gulp.src(config.static_dir + '/template.js')
.pipe(replace({
patterns: [
{
match: '//include',
replacement: fs.readFileSync(config.tmp_dir + '/content.js', 'utf8')
}
],
usePrefix: false
}))
.pipe(gulp.dest(config.tmp_dir));
}

function addHeader(){
return gulp.src(config.tmp_dir + '/template.js')
.pipe(rename(config.script_name))
.pipe(header(fs.readFileSync(config.static_dir + '/header.txt', 'utf8'), { data : pkg } ))
.pipe(gulp.dest(config.dist_dir))
}

function startServer(cb){
server.listen(config.server.options, livereload.listen );
function restart(file) {
server.changed( function( error ) {
if( ! error ) livereload.changed( file.path );
});
}
gulp.watch(config.server.files).on( 'change', restart );
cb();
}

exports.clean = cleanTmpFiles;
exports.clean.description = "clean temporary files";
exports.server = startServer;
exports.server.description = "run development server";
exports.default = gulp.series(
detectDevelopmentFlag,
cleanTmpFiles,
gulp.parallel(utilPartAttach, sourcePartAttach, runPartAttach),
joinScriptParts,
gulp.parallel(joinCssFiles,
gulp.series(addTabulators, fillTemplate, addHeader))
);
exports.default.description = "build project";
exports.default.flags = {
'--development': "add some development features to script"
};

sync(gulp);`

[LeMoussel]

Only tasks registered with task() will be provided to the custom registry.
You must register task() with gulp.registry().set(name, fn)
eg: gulp.registry().set('clean', cleanTmpFiles)