BinlogStreamer WIP.
Merge branch 'master' into new-binlog-streamer
all: format string fixes
bson: errors.New(fmt.Sprintf()) -> fmt.Errorf()
all: for foo, _ := range ... -> for foo := range ...
all: make composite literals use field-keyed elements
Merge pull request #31 from dgryski/go-vet-lint-fixes

Some trivial fixes from "go vet" and "golint"
Merge branch 'master' into new-binlog-streamer
binlog streamer WIP

readEvent function and file position tracker object.
binlog_streamer WIP code complete.

Still need to write tests, and do some more cleanup.
fix typo
fix another typo.
more cleanup & test prep