Split dynamic pipeline manipulation test into a new class / Replace PrefixThreadFactory with DefaultThreadFactory / Port the latest tests from the branch 'out-of-order' written by @normanmaurer
Typo
Fix checkstyle
[#1295] Make sure retain(..) returns the correct WebSocketFrame type
Return correct type on retain(..)
Merge forwardBufferContent and setRemoved()
[#1273] Fix resource leaks in test
Revert "Fix #1075: DefaultChannelHandlerContext.fireChannelSuspended and fireInboundBufferUpdated do not work correctly if handlers with EventExecutor are added or removed from pipeline."

This reverts commit 273948055a5ae38a01f1f24f64026aaa1a8bf0a5, which is
incorrect.

- Related: #1075
[#1297] Make sure ResourceLeakDetector.open(...) is only used after constructing was successful
[#1294] Make sure ByteBuf is released once written to channel
Clean up the pipeline implementation / Ensure Embedded*Channel does not run pending tasks immediately

- Replace ugly 'prev != null' check with explicit event scheduling
- Fix an incorrect flag operation in freeHandlerBuffersAfterRemoval()
- Fix a bug in AbstractEmbeddedChannel.doRegister where it makes pending tasks immediately, where the pending tasks actually triggers inbound events
- Remove unnecessary suppression of inboundBufferUpdated() event in DefaultChannelPipeline, which potentially hides an event ordering bug. Unfortunately, I don't remember why I added it in cca35454d214611792067c89b78f7477aae3a323.
Fix memory leak in DefaultChannelHandlerContext

.. where freeInbound() and freeOutbound() are not called for all contexts

- Fixes #1298