I want to create a text file with a number of pre-calculated rectangle coordinates and it would be mega convenient if I could read this file into the command line, save me having to type each point in by hand (and correcting all the mistakes I will undoubtedly make). Is this possible please?
this is possible in latest master version.
It depends on your operating system, on Windows you can use nightly build installer. On Linux or OS X you have to build from latest source code I think.
It is implemented in 2.2.0 versions. There you will find a button, right beside the command line, which opens a menu containing "Load command file". The command file content should be LibreCAD commands and coordinates, one command per line.
In 2.2.0 versions it is also possible to enter multiple commands and coordinates separated by semicolon.