When talking about LibreCAD 3, the pre alpha stage engine for the next evolution step of LibreCAD is meant. As of the early stage the Wiki and Forum discussions is for development and therefor technical by nature.
Discussions of users, about feature requests, handling and issues refers to LibreCAD 2 and are less technical.
So if you read LibreCAD 3 and are not a developer, you can ignore it with a clear conscience. When LibreCAD 3 will be ready for use, you will get wind of it, I'm sure.
The current stable release of LibreCAD is 2.0.3, the next release 2.0.4 is in the pipeline.
This release versions are marked on github to represent a stable state of the source code. And this are the source codes we build the official download packages from.
Because LibreCAD is open source and platform independent, everybody can build it from source. To identify a binary package, in case any problems arise, there are the SCM, Qt and compiler versions.
The SCM version can become something like 2.0.3-39-gbaaf7df and tells us, that the source code for this version is an intermediate state, 39 commits after the official 2.0.3 state.
The Qt number is the version of the Qt environment that was used to build the binary. This number is something like 4.8.5, 5.0.2 or 5.2.1
Last but not least, the compiler number tells us which compiler was used to build the LibreCAD binary. There are gcc, clang or Microsoft compilers, each with its own version information, which could be used to build LibreCAD.
All this numbers are needed in case of issues, to help us to localize the cause of it. Beside issues in the LibreCAD source codes, problems can arise by errors in Qt libraries or the compiler.