Make function types generic in type definitions (#3168)

* Make function types generic in type definitions

* Add dtslint and tests for type definitions

package.json

@@ -3,7 +3,7 @@
   "version": "0.16.5",
   "description": "A batteries-included SQL query & schema builder for Postgres, MySQL and SQLite3 and the Browser",
   "main": "knex.js",
-  "types": "types/knex.d.ts",
+  "types": "types/index.d.ts",
   "engines": {
     "node": ">=6"
   },
@@ -45,6 +45,7 @@
     "chai-subset-in-order": "^2.1.3",
     "coveralls": "^3.0.3",
     "cross-env": "^5.2.0",
+    "dtslint": "^0.7.1",
     "eslint": "5.16.0",
     "eslint-config-prettier": "^4.1.0",
     "eslint-plugin-import": "^2.16.0",
@@ -85,10 +86,11 @@
     "coveralls": "nyc report --reporter=text-lcov | coveralls",
     "dev": "rimraf ./lib && babel -w src --out-dir lib --copy-files",
     "lint": "eslint '{src,test}/**/*.js'",
+    "lint_types": "dtslint types",
     "plaintest": "mocha --exit -t 10000 -b -R spec test/index.js && npm run tape",
     "plaintest:sqlite": "cross-env DB=sqlite3 npm run plaintest",
     "prepublish": "npm run babel",
-    "pre_test": "npm run lint",
+    "pre_test": "npm run lint && npm run lint_types",
     "bin_test": "cross-env KNEX_PATH=../knex.js KNEX=bin/cli.js jake -f test/jake/Jakefile",
     "tape": "node test/tape/index.js | tap-spec",
     "debug_tape": "node --inspect-brk test/tape/index.js",
@@ -153,7 +155,7 @@
     "LICENSE",
     "CHANGELOG.md",
     "scripts/*",
-    "types/*"
+    "types/index.d.ts"
   ],
   "license": "MIT",
   "tonicExampleFilename": "scripts/runkit-example.js",