title: Angular 5 ng-bootstrap Type 'ElementRef' is not generic err
body: <p>I use angular 5 and ng-bootstrap in these versions:</p>
  
  <pre><code>  "private": true,
    "dependencies": {
      "@angular/animations": "^5.2.0",
      "@angular/common": "^5.2.0",
      "@angular/compiler": "^5.2.0",
      "@angular/core": "^5.2.0",
      "@angular/forms": "^5.2.0",
      "@angular/http": "^5.2.0",
      "@angular/platform-browser": "^5.2.0",
      "@angular/platform-browser-dynamic": "^5.2.0",
      "@angular/router": "^5.2.0",
      "@ng-bootstrap/ng-bootstrap": "^2.1.0",
      "angular-in-memory-web-api": "^0.5.4",
      "angular2-moment": "^1.9.0",
      "bootstrap": "^4.1.1",
      "core-js": "^2.4.1",
      "date-util": "^1.2.1",
      "material-icons": "^0.2.1",
      "ngx-bootstrap": "^3.0.0",
      "normalize.css": "^8.0.0",
      "rxjs": "^5.5.6",
      "zone.js": "^0.8.19"
    },
  </code></pre>
  
  <p>when I get ng serve has this error:</p>
  
  <blockquote>
    <p>**</p>
    
    <p>Failed to compile.</p>
    
    <p>node_modules/@ng-bootstrap/ng-bootstrap/buttons/radio.d.ts(58,96):
    error TS2315: Type 'ElementRef' is not generic.
    node_modules/@ng-bootstrap/ng-bootstrap/datepicker/datepicker-input.d.ts(121,67):
    error TS2315: Type 'ElementRef' is not generic.
    node_modules/@ng-bootstrap/ng-bootstrap/datepicker/datepicker.d.ts(115,208):
    error TS2315: Type 'ElementRef' is not generic.
    node_modules/@ng-bootstrap/ng-bootstrap/dropdown/dropdown.d.ts(12,45):
    error TS2315: Type 'ElementRef' is not generic.
    node_modules/@ng-bootstrap/ng-bootstrap/dropdown/dropdown.d.ts(29,45):
    error TS2315: Type 'ElementRef' is not generic.
    node_modules/@ng-bootstrap/ng-bootstrap/dropdown/dropdown.d.ts(37,44):
    error TS2315: Type 'ElementRef' is not generic.
    node_modules/@ng-bootstrap/ng-bootstrap/modal/modal-window.d.ts(13,40):
    error TS2315: Type 'ElementRef' is not generic.</p>
  </blockquote>