! io: prevent `Terminated` dead letters from IO layer, fixes #704

The breaking nature of this commit comes from the `ConnectionHandler::baseEventPipeline` receiving an additional `tcpConnection: ActorRef` parameter.
= docs: add links from directive usages in examples to docs, fixes #703

Two components:
 * client-side javascript which adds the links
 * build-component that tries to extract the set of directives a source
   file defines

The extraction works by a heuristic regexp that tries to distinguish directive
definitions against other definitions. Directives can explicitly be marked
as such by prefixing them with a block comment, `/* directive */`.
Merge pull request #705 from spray/ticket/704

! io: prevent `Terminated` dead letters from IO layer, fixes #704
Merge pull request #706 from jrudolph/w/link-directive-in-code-snippets

= docs: add links from directive usages in examples to docs, fixes #703
= docs: disable directive links for old milestone releases, refs #703
= docs: general update to non-directive spray-routing docs
= docs: add missing directive stubs, smaller stuff
+ testkit: add `NoAutoHtmlLinkFragments` helper trait, add test to spray-routing-tests
= docs: add path matching docs
= project: fix formatting problem in CHANGELOG
Merge pull request #711 from spray/wip/docs

Misc docs updates, refs #442
= io: fix Tcp.SO.reuseAddress not being applied for outgoing connections, fixes #712

Backport of akka/akka@6ebf6717c9db4c57d5b918342f578a6120e19b5a

See https://github.com/akka/akka/pull/1849
! routing: rename implicit ChunkSizeMagnet constructor and parameters
! routing: rename LoggingParameter constructor parameters for documentation
! routing: `compressResponseIfRequested` used wrong magnet
= routing: reorder method definitions in EncodingDirectives
! routing: make `dynamicIf` a static (= not inner) class

For common usages, API should stay the same.
= build: remove debug println from build
= docs: add links to directives only in spray-routing documentation
= docs: exclude code like `entity = ` from being linked as a directive