Leaflet: Fix the L.tileLayer function typing

The current version was being rejected by Typescript 1.0. The new typing
follows the advice from the Handbook.
Merge pull request #2053 from abustany/fix-leaflet-tilelayer

Leaflet: Fix the L.tileLayer function typing
updated chai-assert.d.ts

fixed chai test
added defs for some (stream) utils
Merge pull request #2246 from Bartvds/chai-assert

updated chai-assert.d.ts
Merge pull request #2247 from Bartvds/streamy

added defs for some (stream) utils
Update watchExpressions definition for $watchGroup

Per https://docs.angularjs.org/api/ng/type/$rootScope.Scope,
the watchExpressions is an array of string OR Function(scope).

Array.<string|Function(scope)>
Added missing definitions, Sys.Debug tests

Added missing properties to Component definitions.
Added debug tests.
Fixed invalid definitions for Debug class, documentation doesn't state
that these methods are static, but the examples appear that Debug is
singleton and methods are static.

Cleaned up Observer definition methods / properties.

Sys.Res Tests have been added and definitions added missing static.
Added Sys.StringBuilder tests
Cleaned up StringBuilder ToString definition overload with optional parameter.
Sys.EventArgs definitions and tests
Region cleanup for Web Essentials //#region support.
added filter method to minimatch

and options optional
fixed lingering typo in semver
Merge pull request #2251 from Bartvds/def/semver2

fixed lingering typo in semver
Merge pull request #2252 from Bartvds/def/minimatch

added filter method to minimatch
fixed semver.Comparator.set
Added NetworkRequestEventArgs and WebRequestManager definitions and tests.
added definition for bl (BufferList)
Merge pull request #2254 from Bartvds/def/semver2

fixed semver.Comparator.set