Update OpenXDK link, the old one is dead
Fix up empty .def file when building DLL without EXPORTs

to silence the dlltool syntax errors which is only confusing.
release: Rename program to make.bas
release: Allow make.bas to generate manifest only
release: Re-add toplevel dirs for main packages
release: Only build zip/tar.gz formats of add-on packages
NSIS installer makefile: Adjust for contrib/release/make.bas again

(main package toplevel dir re-added)
Move new fblogos from 0170fd02 into contrib/ while unused by examples