This updates `fmt` (previously known as `cppformat`) to the most recent available version (at the time of creating this revision)Support the most recent released version of `fmt` (previously known as `cppformat`) available.
In addition, as it is possible to acquire `fmt` as a library from Linux distro repositories, we now attempt to use that by default.This revision also de-bundles the source, The minimum required version for this is `fmt` version 4.0.0as we no longer need to modify it to get the library to work with `pyrogenesis`.
For **Linux** systems who don't have it available, or don't have a recent enough version, the bundled files may be used instead. These are included without modification**Linux**/**BSD**: Users now need to have `fmt` installed from their distribution's package repository. To use them, pass the `--with-bundled-fmt` argument to `update-workspaces.sh`Minimum required version of `fmt` is `4.0.0`.
For **Windows****OSX**: The source is acquired and compiled (in `build-osx-libs.sh`) and **OSX** systems:included/linked automatically,
WARNING: This revision will most likely break builds on Windows and, possibly, OSX. I do not have access to either**Windows**: The relevant header files are retained, so am unable to confirm or remedand along with a pre-built library (not actually included in the revision yet) are to be the only thisng bundled.