Use double quotes instead of single quotes for passing commands to po…

…wershell/cmd.exe

As recommended by FreeRDP documentation

User slirp for user-mode networking

Update updater.py

Various changes, making freerdp connection more robust and flexible

Update updater.py

Update updater.py

Bug fixes

fixes #69 and #70

Various improvements to setup

hopefully fixing #65, #61, and #60

Add checkboxes for xfreerdp "hidef" and "multimon" options in GUI

Improvements to container shutdown and restart and Python dependency …

…detection

Should fix #59