* [vcpkg docs] add docs for manifest files
These are just for the maintainer docs,
not user docs.
* [vcpkg] EBNF-ify platform expression parsing
this modifies nothing about what strings are accepted or rejected,
it just moves stuff around.
also adds tests.
* [vcpkg docs] add manifest mode example
* [wip] docs for augustin
also fix tabs
* [vcpkg manifest] switch to using maps for features
* Apply suggestions from code review
* un-experimentize format-manifest
* flesh out the user manifest mode docs
* CRs
* billy CRs
* final personal pass-thru
* [vcpkg] Add new function vcpkg_copy_tools
* [cpuinfo][czmq][nanomsg][uriparser] Use vcpkg_copy_tools
* [czmq] Clean even tools are not copied
[libsvm][zyre] Use vcpkg_copy_tools
* [vcpkg-copy-tools] Clean debug/bin
This should fix czmq build error
* [czmq] czmq does not have BUILD_TOOLS option
* [vcpkg] Split clean logic into another function
* [cpuinfo][czmq][nanomsg][uriparser] Fix calling of vcpkg_copy_tools
* [zyre] Fix regression error
* [vcpkg] Update try_remove_empty_directory
* [libsvm] Fix vcpkg_copy_tools call
