Add Meson/bt as alternative build and packaging system; make enum deserialisation more robust

[matty0ung]

The enum deserialisation is just adding a fallback for case-insensitive matching.

The Meson build stuff is mostly in two new files at the top-level directory: bt and meson.build. The former is a Python script that can:

• install almost all the necessary dependencies for building the software
• set up the Meson build environment (in the mbuild subdirectory)
• after a Meson build is done (via cd mbuild; meson compile), package up the software (into mbuild/packages subtree)

Note that the current CMake/CPack build is pretty much unaffected by this new work. You can still run all the regular CMake stuff in the build subdirectory. CMake/CPack builds should continue to function as correctly as they do now (ie just fine on Windows and Linux, and fine except for package building on Mac).

[penguinpee]

Nice! I'll give that a try as the build backend for the Fedora package. Are there plans for switching to Meson completely?

[matty0ung]

Nice! I'll give that a try as the build backend for the Fedora package. Are there plans for switching to Meson completely?

There are still a few glitches to iron out, but once things seem like they are working, we'll see what folks think.

Personally I think using Meson simplifies the build, partly because Meson doesn't try to do all the things that CMake does, so you end up doing all the "not-build" things in a regular scripting language. And, for non-trivial scripting, I think Python is nicer than bash. Of course moving away from CPack it makes packaging less automagical, but CPack has been far from trouble-free, and the upside of doing things more explicitly is that we then have more control over library dependency and other packaging joys. Certainly doing the scripting has helped me understand a lot better how packaging works on Windows and Mac!