support non-local remote transports (#57)

* support non-local remote transports

* fix LogosResult

* allow getting client over specific transport

* fix ssl

* investiage ssl error

* pr comments

* allow transport set configuration on any module

* pr comments

* add docs

* pr comments

* propagate only non-qt dependencies

* restore ABI compatibility

cpp/implementations/plain/io_context_pool.cpp

@@ -0,0 +1,28 @@
+#include "io_context_pool.h"
+
+namespace logos::plain {
+
+IoContextPool::IoContextPool()
+    : m_ioc()
+    , m_guard(boost::asio::make_work_guard(m_ioc))
+    , m_worker([this]{ m_ioc.run(); })
+{
+}
+
+IoContextPool::~IoContextPool()
+{
+    // Drop the work guard so run() can return once all outstanding work
+    // completes, then stop forcefully if something lingers.
+    m_guard.reset();
+    m_ioc.stop();
+    if (m_worker.joinable())
+        m_worker.join();
+}
+
+IoContextPool& IoContextPool::shared()
+{
+    static IoContextPool pool;
+    return pool;
+}
+
+} // namespace logos::plain