mmap: initial commit
examples: add some of derived from original
batch: introduce mnl_nlmsg_batch_reset_buffer() for mmap

and add example using it.
github: add README.md
parse: change offset type

to fit with mnl_nlmsg_get_payload_offset()
seq, portid: change type to uint32_t

following struct nlmsghdr
examples: use mnl_nlmsg_get_payload()

not increment (nlmsghdr) pointer
document: mnl_socket_open

fix return value on error
attr: validate MNL_TYPE_MSEC same as MNL_TYPE_U64
Revert "seq, portid: change type to uint32_t"

This reverts commit c015a39655877d35fa917c74852637a71a949f57.

We cannot change the API, it may break compilation of existing
applications.
Revert "parse: change offset type"

We cannot change this, it breaks the ABI.

This reverts commit 3223cba908efaba6738ec59222278ff248fa9cdf.