Deflect 0.14.0

• 191:
  DesktopStreamer: default host and other options can be specified on the
  command line.
• 190:
  DesktopStreamer: jpeg compression can be turned on or off.
• 188:
  The default constructors for Stream and Observer can read the port variable
  from the DEFLECT_HOST environment variable (using hostname[:port]).
• 184:
  Images in OpenGL format (bottom-up row order) can be streamed directly,
  replacing the need for ImageWrapper::swapYAxis() in user code.
• 179:
  Added stopping() signal to qt::QuickRenderer for GL cleanup operations.
• 177:
  Improve stream error handling
  • Catch errors regarding invalid JPEG quality values
  • Set exceptions in returned futures on errors
• 176:
  OPT: Lock-free request queueing for multi-threaded stream clients (e.g. KNL)
• 175:
  Add deflect::Observer which can be used to only receive events w/o the need
  to send images
• 174:
  Performance improvements for sending small images (tested with 64x64):
  directly compress them in the call thread
• 173:
  Fix server: disabling system proxy which are default starting Qt 5.8