install .pdb files when available

generate separate ab/abs binaries, following traditional Windows practice

add missing utility httxt2dbm

provide options to disable installation of manual and .pdb files

tweak todo list


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1521821 13f79535-47bb-0310-9956-ffa450edef68