open express.d.ts interfaces

- provides open interfaces for Request, Response, Application
- express's interfaces remain the same, but extend the open ones
amend passport.d.ts

- passport.d.ts has been amended to merge its Request extensions into
express's Request interface.
- removed now-unnecessary type coercions from passport-test.ts
HighchartsLegendOptions.useHTML?: boolean

HighchartsLegendOptions.useHTML is boolean property, not numeric.

Sometimes i'm thinking that I'm the first person in the world who is using these definitions (
Merge pull request #1994 from yortus/open-express.d.ts-interfaces

Open express.d.ts interfaces
add diff/diff.d.ts
improve diff-tests.ts
Merge pull request #2013 from enternet/patch-8

HighchartsLegendOptions.useHTML?: boolean
Merge pull request #2018 from vvakame/add-jsdiff

add diff/diff.d.ts