update changelog for v0.9.0

update changelog

update changelog

update changelog

add changelog file

Merge pull request #38 from paulmach/state_at

replication: search for state/sequence number by timestamp

Merge pull request #36 from OlafFlebbeBosch/protobuf

protobuf: port to google protobuf

Merge pull request #30 from paulmach/filter

osmpbf: add filter functions

Merge pull request #26 from paulmach/no-preallocate

osmpbf: do not preallocate nodes

Merge pull request #22 from oflebbe/master

Limit amount of channel buffers