Ensure PooledByteBuf.init() is not called with null memory
Remove ChannelBuf/ByteBuf.Unsafe

- Fixes #826
Unsafe.isFreed(), free(), suspend/resumeIntermediaryAllocations() are not that dangerous. internalNioBuffer() and internalNioBuffers() are dangerous but it seems like nobody is using it even inside Netty. Removing those two methods also removes the necessity to keep Unsafe interface at all.
Rename ChannelBuf to Buf and ChannelBufType to BufType

- Fixes #825
Add IllegalBufferAccessException and checks on MessageBuf impls

- Related: #827
Add proper boundary / freeness check on ByteBuf impls

- Fixes #827
Fix checkstyle
Add missing free() on SpdySessionHandler buffers
Add some javadocs
Do not call inbound event methods directly

- Fixes #831

This commit ensures the following events are never triggered as a direct
invocation if they are triggered via ChannelPipeline.fire*():

- channelInactive
- channelUnregistered
- exceptionCaught

This commit also fixes the following issues surfaced by this fix:

- Embedded channel implementations run scheduled tasks too early
- SpdySessionHandlerTest tries to generate inbound data even after the
  channel is closed.
- AioSocketChannel enters into an infinite loop on I/O error.
Fix checkstyle
DatagramPacket should be final
Fix #814 - Prevent IllegalBufferAccessException on write() and flush()

- Also fixed a incorrect port of SpdySessionHandler
  - Previously, it closed the connection too early when sending a GOAWAY frame
  - After this fix, SpdySessionHandlerTest now passes again without the previous fix
Remove cruft
Next round of javadocs cleanup and fixes. Also limit the visibility of FailedChannelFuture
more javadocs
Add javadocs in the oio package and also fix some intellij warnings
Fix config
Add javadocs to AIO and also fix a few warnings
Add Snappy compression codec
Remove bad Javadoc in SCTP classes.