(core) Speed up and upgrade build.

Summary:
- Upgrades to build-related packages:
  - Upgrade typescript, related libraries and typings.
  - Upgrade webpack, eslint; add tsc-watch, node-dev, eslint_d.

- Build organization changes:
  - Build webpack from original typescript, transpiling only; with errors still
    reported by a background tsc watching process.

- Typescript-related changes:
  - Reduce imports of AWS dependencies (very noticeable speedup)
  - Avoid auto-loading global @types
  - Client code is now built with isolatedModules flag (for safe transpilation)
  - Use allowJs to avoid copying JS files manually.

- Linting changes
  - Enhance Arcanist ESLintLinter to run before/after commands, and set up to use eslint_d
  - Update eslint config, and include .eslintignore to avoid linting generated files.
  - Include a bunch of eslint-prompted and eslint-generated fixes
  - Add no-unused-expression rule to eslint, and fix a few warnings about it

- Other items:
  - Refactor cssInput to avoid circular dependency
  - Remove a bit of unused code, libraries, dependencies

Test Plan: No behavior changes, all existing tests pass. There are 30 tests fewer reported because `test_gpath.py` was removed (it's been unused for years)

Reviewers: paulfitz

Reviewed By: paulfitz

Subscribers: paulfitz

Differential Revision: https://phab.getgrist.com/D3498

app/server/declarations.d.ts

@@ -18,33 +18,6 @@ declare module "bluebird" {
   class Disposer<T> {}
 }
 
-// TODO This is a module by Grist Labs; we should add index.d.ts to it.
-declare module "@gristlabs/basket-api" {
-  interface Item { [colId: string]: any; }
-  interface ColValues { [colId: string]: any[]; }
-  interface AuthToken { [authProvider: string]: string; }
-
-  class Basket {
-    public static addBasket(login: AuthToken): Promise<string>;
-    public static getBaskets(login: AuthToken): Promise<string[]>;
-
-    public basketId: Readonly<string>;
-    public apiKey: Readonly<string|undefined>;
-
-    constructor(basketId: string, apiKey?: string);
-    public addTable(optTableId: string): Promise<string>;
-    public getTable(tableId: string): Promise<Item[]>;
-    public renameTable(oldTableId: string, newTableId: string): Promise<void>;
-    public replaceTableData(tableId: string, columnValues: ColValues): Promise<void>;
-    public deleteTable(tableId: string): Promise<void>;
-    public getTables(): Promise<string[]>;
-    public uploadAttachment(attachmentId: string, attachment: Buffer): Promise<void>;
-    public delete(login: AuthToken): Promise<void>;
-  }
-  namespace Basket {}
-  export = Basket;
-}
-
 // Used in one place, and the typings are almost entirely unhelpful.
 declare module "multiparty";