Add support for ad.doubleclick.net track link

[rayou]

Example URLs:

- http://ad.doubleclick.net/clk;274204538;98873843;y?http://www.food.com/recipe/cuban-pork-adobo-salad-501729
- http://ad.doubleclick.net/clk;272664759;101583304;i?http://www.porkbeinspired.com/RecipeDetail/2770/Cuban_Pork_Adobo_Salad.aspx

As you can see, doubleclick track link doesn't put target URL in any parameters, targetParam method can't fit this case.

I'd like to propose to use regex for parsing target URLs also keep the current "param" parse method:

Add targetRegex:

  {
    name: 'Doubleclick',
    targetRegex: /\?(.*)$/,
//  targetParam: "url", 
    patterns: [
      `${SCHEMA}ad.doubleclick.net${PATH}?`
    ],
    types: ['main_frame']
  }

OR

Add parseMethod to make it explicit:

  {
    name: 'Doubleclick',
    parseMethod: "regex", // Accepts: "param" | "regex" 
    target: /\?(.*)$/, // Accept types: string | regex
    patterns: [
      `${SCHEMA}ad.doubleclick.net${PATH}?`
    ],
    types: ['main_frame']
  }

OR

Use target: (one property to rule them all)

  {
    name: 'Doubleclick',
    target: /\?(.*)$/, // Accept types: string | regex
    patterns: [
      `${SCHEMA}ad.doubleclick.net${PATH}?`
    ],
    types: ['main_frame']
  }

However, this implementation requires a major revamp, so would like to hear some feedback.