Fix numerous thread/socket lifecycle crashes and TLS/epoll write-stall busy-loop

Thread/EPoll lifecycle:
- Thread::~Thread() now actually joins/frees its worker thread (was
  empty - the OS thread kept running against already-freed EPoll/Socket
  objects on any early teardown, a confirmed "double free" crash)
- EPoll::~EPoll() calls stop() if never explicitly stopped, for the
  same reason
- epoll_wait() now uses a 1s timeout instead of blocking forever, so a
  worker thread can actually notice isStopping() and let itself be
  joined
- EPoll::processCommand() iterated threads by value, silently
  double-freeing the real vector's Thread the moment each copy went
  out of scope
- ThreadScope gained onThreadStart()/onThreadEnd() hooks (actually
  wired up now - the constructor that was supposed to store the scope
  discarded it) for per-thread C-library init (e.g. MySQL client)

Socket/TCPSocket/TLS:
- Socket::writeSocket(): give up and shut down a connection after 50
  consecutive zero-progress sends instead of retrying forever -
  SSL_ERROR_WANT_READ on a write needs a READ to make progress, but
  resetSocket() re-arms EPOLLWRNORM regardless, which an
  already-writable TCP socket satisfies immediately - a real stuck
  connection generated 55GB, then 12.9GB of debug log this way before
  being caught
- Socket::writeSocket() now honors sendData()'s actual return value
  (previously discarded, entry popped unconditionally after one call) -
  a large response could get silently truncated past what fit in one
  write()/SSL_write() call
- TLS::registerSocket()/sendData()/receiveData(): `initialized` now
  only goes true once SSL_set_fd() has actually succeeded, and
  sendData()/receiveData() check it first - fixes a real SIGSEGV where
  a new session's own queued greeting could reach SSL_write() on a
  different epoll thread before this session's handshake setup had run
- TCPServer::connectionRequest() now performs the TLS handshake ON THE
  ACCEPTED SESSION, not the listening server itself (was building SSL
  state on the wrong object, leaving every session's own `ssl`
  uninitialized)
- TCPServer::receiveData() always uses the plain (non-TLS) read path -
  the listening socket is never itself a TLS peer
- TCPSocket's block-mode literal reading used an unset `blockLength`
  field instead of `blockSize`, and could busy-spin forever on a
  multi-packet literal
- TCPSocket line scanning replaced an unbounded strcspn() (assumes a
  NUL-terminated buffer; read past a non-NUL-terminated receive buffer
  into adjacent heap memory) with a bounds-checked memchr() scan

Protocol/session handling:
- CommandList::processRequest() now case-folds the command keyword
  before lookup - SMTP/POP3/IMAP commands are spec-required to be
  case-insensitive; a client sending "Mail From:" instead of
  "MAIL FROM:" previously failed to dispatch at all
- TCPSession::protocol() no longer drops blank lines while a handler
  has grabbed input (e.g. __SMTP_DATA reading a message body, an IMAP
  APPEND literal) - those handlers depend on seeing blank lines as
  real content, not commands; this silently corrupted any message body
  containing a blank line
- TCPSession's uuid alias fixed: streaming a raw uuid_t via operator<<
  triggered libstdc++'s unsigned-char* overload (strlen() on 16 binary
  bytes, a real stack-buffer-overflow read), and `alias` pointed at a
  stack-local that was already destroyed by the time the constructor
  returned
- INotify::processEvent() only treats event->name as a NUL-terminated
  string when event->len > 0 (per inotify(7)) instead of unconditional
  strlen() on a field the kernel doesn't guarantee is even present -
  a confirmed heap-buffer-overflow read that had been misdiagnosed as
  a MySQL thread-safety issue

ThreadScope.h

@@ -3,10 +3,34 @@
 
 namespace core {
 
+   ///
+   /// ThreadScope
+   ///
+   /// Extension point for per-OS-thread setup/teardown in an EPoll worker
+   /// pool. EPoll's threads are long-lived (one persistent event loop per
+   /// thread, for the process's whole lifetime, not spawned per-request) -
+   /// onThreadStart() runs once at the top of each thread, before it
+   /// enters its event loop; onThreadEnd() runs once as that thread is
+   /// shutting down. A single ThreadScope instance is shared across every
+   /// worker thread (passed to EPoll::start()), so overrides should only
+   /// touch thread-LOCAL state from these hooks, never the ThreadScope
+   /// object's own fields, without their own synchronization.
+   ///
+   /// Concrete motivating case: a C library that requires explicit
+   /// per-thread initialization before use from a multi-threaded program
+   /// (e.g. the MySQL client library's mysql_thread_init()/
+   /// mysql_thread_end() - see APIServer's MysqlThreadScope) has no other
+   /// clean way to hook into an EPoll worker thread's lifetime.
+   ///
+
    class ThreadScope {
 
     public:
       ThreadScope() {}
+      virtual ~ThreadScope() {}
+
+      virtual void onThreadStart() {}
+      virtual void onThreadEnd() {}
 
    };