Packages.csv: Add column for VistA Document Library App Id

The VistA Document Library at http://www.va.gov/vdl identifies packages
with an integer "appid" and publishes documentation at URLs of the form

 http://www.va.gov/vdl/application.asp?appid=$appid

Add a column to Packages.csv called "VDL ID" to hold the appid for each
package.
Packages.csv: Fill in VDL ID column for known packages

Add the VDL appid for each package whose VDL page is known.
Add VDL links to Patches/<package>/README.rst files

Add a Documentation section to every package README.rst file to link to
its VistA Document Library page.

Use the following shell code:

tail -n +2 Packages.csv |
egrep '^[^,]+' |
while IFS=, read pkg dir _ _ _ _ vdl; do
  if test -n "$vdl"; then
    sed -i '/^---*$/ {h;d} # hold section header lines for next cycle
/^Patches$/ {# If this was preceded by a header line, prepend our section.
x;/^---*$/i\
-------------\
Documentation\
-------------\
\
Documentation for this package is available in the `VistA Document Library`_.\
\
.. _`VistA Document Library`: http://www.va.gov/vdl/application.asp?appid='"$vdl"'\

;x}
{x;/./{p;s/.*//};x} # dump any held lines
' "Packages/$dir/README.rst"
  fi
done