Support non-blocking and async operation.

src/e-server:
	* src/GdbServer.cpp: Rename currentCThread and mContinueThread and
	currentGThread as mGeneralThread throughout.
	(GdbServer::GdbServer): initialize nNotifyingP.
	(GdbServer::rspServer): reset mNotifyingP on new connection.
	(GdbServer::rspClientRequest): Use unified version of getPkt for
	non-stop.  Reset mNotifyingP on '?' packet.
	(GdbServer::rspClientNotifications): Provide implementation.
	(GdbServer::readThreadId): Created.
	(GdbServer::getThread): Use our own assert method.
	(GdbServer::rspReportStopped): Deal with zero threads in
	non-stop mode.  Use hex format for thread IDs.
	(GdbServer::findStopReason): Deal with case of reset when we are
	at location 0.
	(GdbServer::rspContinueGeneric): No reply in non-stop mode.
	(GdbServer::rspSetThread): Use readThreadId to get TID.
	(GdbServer::rspQuery): -1 is not a valid return.
	(GdbServer::rspIsThreadAlive): Use readThreadId to get TID.
	(GdbServer::rspVpkt): Report support of 's' packets with vCont,
	even though we don't think we'll get them.
	(GdbServer::rspVCont): Clear mNotifyingP on new continue.
	* src/GdbServer.h: Rename currentCThread and mContinueThread and
	currentGThread as mGeneralThread throughout.  Add mNotifyingP and
	declarations of new member methods.
	* src/RspConnection.cpp (RspConnection::RspConnection): Subsume
	functionality of rspInit.
	(RspConnection::rspInit): Deleted.
	(RspConnection::rspConnect): Remove obsolete servername code.
	(RspConnection::getPkt): Modify to allow non-blocking reads
	(bool RspConnection::getPktNonBlock): Deleted.
	(RspConnection::putNotification): Created.
	(RspConnection::getBreak): Simplified to use non-blocking read.
	(RspConnection::putRspChar): Always blocking.
	(RspConnection::getRspChar): Provide option to be non-blocking.
	(RspConnection::setBlocking): Created.
	(RspConnection::setNonBlocking): Created.
	* src/RspConnection.h: Add new methods.
	* src/TargetControlHardware.cpp (TargetControlHardware::readMem):
	Don't put out warning message.
	(TargetControlHardware::writeMem): Likewise.
	* src/Thread.cpp (Thread::readMem32): Clearer error message.
	(Thread::readMem16): Likewise.
	(Thread::readMem8): Likewise.
	(Thread::readReg): Likewise.
	(Utils::rspAssert): Created.
	* src/Utils.h: Added new method.