CMakeLists - removed OpenThreads section (not needed and makes compiling on CentOS not working)

Peer: only log bytes sent if actually done - i.e. dont report 0 bytes left...
seems like 'Threads ' is needed for pthread anyway (?)
post stop instead of close/cancel - close resulted in a race condition causing a deadline timer call just after a connect to leave socket unconnected when queried in VersionFilter
Removed shutdown/cancel from Peer::stop - we just rely on the destructor to clean up
enabled easy swithcing off of multithreaded verification of signatures
Fixed forgotten addition - don't flush if we are already flushing - doh! thought I had that one comitted already...
Deleted a few commented out lines from last commit
A lot of network bugfixes:
* Did not announce the right version to inbound connections - FIXED
* Did never disconnect inbound clients causing a lot of strange behaviour
* Made outbound connections more robust and fixed race conditions
fixed sql errors in getSpentOutputs and getOutputs.
fixed logic error in handle_async_block
fixed trying to access closed socket (Bad File Descriptor exception) by ensuring the socket is open before executing the actual handle_read/write
Improved the GetBlock rpc call
fixed the rpc GET command
Merge pull request #75 from domob1812/fix-median

Fix the peer manager's median calculation.
Super - thanks for fixing this - I never had the issue myself though - could be due to number of peers ?