New module backports
Various patches that apply to
master from the new modules branch. This helps to keep that branch smaller and more manageable.
I'm unsure about the removal of the TclTk module (though I really don't want to have to port it to the third party import setup and the new module system…). Our copy is really old (last updated in 2013: 1b1d6172) and if someone needs TclTk I'd expect that the system version is suitable.