Add no-else-return and update no-unused-vars and keyword-spacing

[Rautherdir]

Sets no-else-return to error

An example of previously working code that will now have an error:

if(condition){
	return false;
}else{
	return true;
}

Example of working code with this rule:

if(condition){
	return false;
}
return true;

Sets the ignoreRestSiblings option to true for the no-unused-vars rule

An example of code that would previously have an error but would now work:

const {unused, ...options} = opts;

Example of code that would work before this change:

const {...options} = opts;
delete options.unused;

Adds this: {before: true, after: false} to the overrides option of keyword-spacing

An example of code that would previously have an error but would now work:

if(this.index > this.highestIndex){
	this.highestIndex = this.index;
}

An attempted solution that has an error due to space-infix-ops:

if(this.index >this.highestIndex{
	this.highestIndex = this.index;
}

Example of code that would work before this change:

let highestIndex = this.highestIndex;
if(this.index > highestIndex){
	this.highestIndex = this.index;
}

[Cherry]

Thanks, merged and released in 2.1.4. 🎉