Provides a place to record work that is pending due to
library, compiler or language restrictions.
Because some of this work will be pending for several years
until supported distros support the relevant versions, having
this centrally documented prevents it being forgotten.
Also includes current distro versions for extant "LTS"
distros that are likely to be the distros holding back
library versions.
Only includes things we currently actually do work around
in the code, or things that are direct C++ replacements
(e.g. Boost libraries being adopted to C++).
This is as opposed to more opinion-based "we should
do it this way, it's better" things, which should be
proposed for discussion first.