Exposing too many API that should be private

[bigboss2063]

Since the current nutsdb package structure is flat, all internal methods and variables can be changed to private, and only part of the user API should be exposed.

For example, The method SubmitBucket in tx.go should rename to submitBucket.

[ziscky]

Hey, I would like to work on this issue.

[bigboss2063]

Hey, I would like to work on this issue.

Assigned to you. Thanks.😁

[ziscky]

Hey @bigboss2063 PR is ready, should I also have changed the internal types e.g Event, Record to be unexported ? I left them as is but I changed the creator methods to newEvent and newRecord

[bigboss2063]

Hey @bigboss2063 PR is ready, should I also have changed the internal types e.g Event, Record to be unexported ? I left them as is but I changed the creator methods to newEvent and newRecord

yeap. I think we should change them all.

[ziscky]

@bigboss2063 I think PR is ready now with the extra changes

[bigboss2063]

Wow! It's a very big change. I need some time to review🤣.