Bug fix for possibly uninitialized variable in pollset:remove()
LDAP functions add(), compare(), delete(), modify(), rename()

Based on LuaLDAP, contributed by zhiguo zhao, modified by myself.
Silence etc/make.lua by default
New functions apr.file_truncate(), file:truncate()
Make apr.host_to_addr() return one *or more* results
Merge https://github.com/xolox/lua-apr