Fixes: RIPD-1521
Switch to pure doxygen HTML for developer docs. Remove docca/boostbook
system. Convert consensus document to markdown. Add existing markdown
files to doxygen input set. Fix some image paths and scale images for
use with MD links. Rename/cleanup some files for consistency.
Add pipeline logic for windows slaves. Add ninja and parallel test run
option. Add make doc target build in build-and-test.sh. Cleanup README
files. Add nounity windows build. Add link to jenkins summary table.
Add rippled_classic build (win). Improve formatting of summary table.
The install process will first fetch the tip of the master branch
to build the latest official rippled release. It will also create
all the necessary data directories in /var.
An optional systemd service definition file is included.
