Merge branch 'vcxproj' into prepare-for-2.20.0-rc0

These patches will supersede the corresponding patches that are already
in the branch thicket, during the next merging-rebase.

That merging-rebase is scheduled for v2.20.0-rc0, which is scheduled
later tonight. However, the plan is to hold off with pushing this to
`master` until the merging-rebase to v2.20.0-rc1.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho