ns-3.45 release this month

[Tom Henderson]

Hi all, apologies for being a bit more quiet on development than usual
in this cycle (due to non-work distractions this spring) but we do have
a release scheduled for May and I would like to proceed with that plan
because I don't see any blockers.

I'd like to aim for a code freeze date of mid-May (May 16).  We have
about 20 or so items in the tracker marked for ns-3.45 milestone and I'm
not sure whether that will be enough time, especially for things like
windows visual studio clang support (should that be retargeted to an
ns-3.46 cycle merge?).  Please update your MRs and/or comment on whether
May 16 is not enough time for you.

On another point, Sebastien, Peter, and I met recently to talk about the
strongly typed units/quantities topic because Sebastien urgently wants
to resolve this.  We agreed in that discussion to continue evaluating
the solution in !2085 with a complete cutover of the wifi module to at
least cover all power quantities and perhaps all frequency quantities. 
This won't be for ns-3.45 but perhaps ns-3.46 timeframe.  I said that
I'd get my current update to compile and then Sebastien and I will take
a further look at progressing it.

- Tom