Add feature option to block opening new windows

### Prerequisites

Please answer the following questions for yourself before submitting an issue. **YOU MAY DELETE THE PREREQUISITES SECTION.**

- [X] I am running the latest version
- [X] I checked the documentation and found no answer
- [X] I checked to make sure that this issue has not already been filed

### Problem Description

Some websites use tricks to disguise third-party requests as first-party request causing them to open a new window with an advertisement

### Proposed Solution

Identical to uBlockOrigin add an option to block opening new windows (have a look at the $popunder option of uBlockOrigin)

### Alternatives Considered

In stead of writing advanced rules, blocking opening new windows simply does the trick for me (using uBO's $popunder in example below):

||*$popup,popunder,domain=nastywebsite.com
||nastywebsite.com$popup,popunder

### Additional Information

I know blocking opening new windows can lead to website breakage, but these 'as first-party spoofed third-party advertising' is easily blocked with the two rules I wrote above