Adding a general handler for upgrading protocols

Adding full implementation for cleartext upgrade from HTTP to HTTP/2.
Limit the number of bytes to copy per Unsafe.copyMemory()

Motivation:

During a large memory copy, safepoint polling is diabled, hindering
accurate profiling.

Modifications:

Only copy up to 1 MiB per Unsafe.copyMemory()

Result:

Potentially more reliable performance
Checkstyle
Clean up example execution

Motivation:

- example/pom.xml has quite a bit of duplication.
- We expect that we depend on npn-boot in more than one module in the
  near future. (e.g. handler, codec-http, and codec-http2)

Modification:

- Deduplicate the profiles in example/pom.xml
- Move the build configuration related with npn-boot to the parent pom.
- Add run-example.sh that helps a user launch an example easily

Result:

- Cleaner build files
- Easier to add a new example
- Easier to launch an example
- Easier to run the tests that relies on npn-boot in the future
Fix a problem where all classes are compiled again

Motivation:

Due to a known problem[1] of maven-compiler-plugin, our build always
compiles everything from scratch, which is waste of time.

Modifications:

Exclude package-info.java from the source list.

Result:

Much shorter build time.

[1]: https://jira.codehaus.org/browse/MCOMPILER-205
Fix a build problem with JDK 8

Motivation:

Build fails with JDK 8 because npn-boot does not work with JDK 8

Modifications:

Do not specify bootclasspath when on JDK 8

Result:

Build is green again.
Clean up the execution mechanism of examples

Motivation:

- There's no way to pass an argument to an example.
- Assigning a Maven profile for each example is an overkill.
  It makes the pom.xml crowded.

Modifications:

- Remove example profiles from example/pom.xml
- Keep the list of examples in run-example.sh
- run-example.sh passes all options to exec-maven-plugin.
  For example, we can now do this:

    ./run-example.sh -Dssl -Dport=443 http-server

Result:

- It's much easier to add a new example and provide an easy way to
  launch it.
- We can still pass an arbitrary argument to the example being launched.
  (I'll update all examples to make them get their options from system
  properties rather than from args[].
Improve run-example.sh

- More usage example
- Newlines for prettier output
Fix resource leak in DefaultHttp2FrameIOTest
Bash 3 compatibility

Motivation:

Mac OS X ships Bash 3, and it does not have an associative array
(declare -A).

Modifications:

Do not use an associative array.

Result:

Can run examples on Mac OS X using run-example.sh
Add unified NextProtoNego extension support to SslContext

Motivation:

- OpenSslEngine and JDK SSLEngine (+ Jetty NPN) have different APIs to
  support NextProtoNego extension.
  - It is impossible to configure NPN with SslContext when the provider
    type is JDK.

Modification:

- Implement NextProtoNego extension by overriding the behavior of
  SSLSession.getProtocol() for both OpenSSLEngine and JDK SSLEngine.
  - SSLEngine.getProtocol() returns a string delimited by a colon (':')
    where the first component is the transport protosol (e.g. TLSv1.2)
    and the second component is the name of the application protocol
- Remove the direct reference of Jetty NPN classes from the examples
- Add SslContext.newApplicationProtocolSelector

Result:

- A user can now use both JDK SSLEngine and OpenSslEngine for NPN-based
  protocols such as HTTP2 and SPDY
Update the instruction for running SPDY examples
Escape a colon in protocol names
Fix NPE in OpenSslEngine
Merge branch 'master' of https://github.com/netty/netty into http2

Conflicts:
	example/src/main/java/io/netty/example/http2/client/Http2Client.java
	example/src/main/java/io/netty/example/http2/client/Http2ClientInitializer.java
	example/src/main/java/io/netty/example/http2/server/Http2Server.java
	example/src/main/java/io/netty/example/http2/server/Http2ServerInitializer.java
Merge pull request #2496 from nmittler/http2

Adding a general handler for upgrading protocols
Future compatibility with TLS ALPN

Motivation:

According to TLS ALPN draft-05, a client sends the list of the supported
protocols and a server responds with the selected protocol, which is
different from NPN.  Therefore, ApplicationProtocolSelector won't work
with ALPN

Modifications:

- Use Iterable<String> to list the supported protocols on the client
  side, rather than using ApplicationProtocolSelector
- Remove ApplicationProtocolSelector

Result:

Future compatibility with TLS ALPN
Checkstyle
Fix NPE
Fix an event ordering issue

Motivation:

In the early days of 5.0, we merged ChannelInboundHandler and
ChannelOutboundHandler into ChannelHandler, and introduced the
annotation called 'Skip'.  The annotation 'Skip' was introduced to
determine which handler methods are no-op (i.e. simply forwarding the
event to the next handler) so that DefaultChannelHandlerContext doesn't
even need to submit an event-invoking task to an EventExecutor,
significantly reducing the context switches.

However, this introduced a regression for the handlers which implemented
write() but not flush(). Because flush() was skippable for such
handlers, flush() event went through to the next handler before write() does.

To address this problem, we came up with a naive workaround that sets
MASK_FLUSH when MASK_WRITE is set.

Although the previous workaround works fine for many cases, we still
seem to have an event ordering problem.  We keep seeing the intermittant
failure of LocalTransportThreadModelTest.testStagedExecution(), because
other handler methods are still skipped.

Modifications:

We do not skip the execution of handler methods annotated with 'Skip'
unless all inbound methods (or all outbound methods) are marked with
'Skip'.

Result:

This change Brings back the event ordering behavior of 4.x, making
LocalTransportThreadModelTest.testStagedExecution() pass.