Refactor guplfile.js

[Raruto]

First rewrite of the gulpfile to try to make it easier for anyone to understand:

• move declare statements to top
• avoid some negative conditionals
• comment out dead code
• use multiline comments for tasks
• inline some unnecessary functions definitions

Related to: #29

[volterra79]

@Raruto done. I checked and i need to push a commit to fix an issue on gulpfile regarding 'browser-sync' task on line 322:
const port = conf.localServerPort ?? 3000; to const port = conf.localServerPort || 3000;

[Raruto]

@volterra79

ok, but keep in mind that the following statement:

const port = conf.localServerPort ?? 3000;

is equivalent to the following (which was the starting code):

const port = conf.localServerPort ? conf.localServerPort : 3000;

and not to:

const port = conf.localServerPort || 3000;

or at least I think so

[volterra79]

@Raruto you are right. If run npm run default using

const port = conf.localServerPort ?? 3000; 

i receive an error

`const port = conf.localServerPort ?? 3000;
^

SyntaxError: Unexpected token '?'
at wrapSafe (internal/modules/cjs/loader.js:1047:16)
at Module._compile (internal/modules/cjs/loader.js:1097:27)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1153:10)
at Module.load (internal/modules/cjs/loader.js:977:32)
at Function.Module._load (internal/modules/cjs/loader.js:877:14)
at Module.require (internal/modules/cjs/loader.js:1019:19)
at require (internal/modules/cjs/helpers.js:77:18)
`

[Raruto]

yes, there is probably a project dependency with does not yet support the nullish coalescing operator.

[volterra79]

@Raruto i investigate on it