Add feature to eosio-blocklog have option to print the blocks.log and ship version

[matthewdarwin]

Add a new feature eosio-blocklog have option to print the blocks.log and ship version.

For the upgrade guide, we want to be able to tell users when they can use the 2.0 blocks / ship and when they can't. We could just say if you're running 2.1 then throw them out and start over, but that's throwing things out that can possibly be used in mandel 3.1

The format of blocks.log and ship is dependent on the version where you created the files, not the last version using them. This makes it difficult to tell what is the current state as you don't remember what you did X time in the past when you did the upgrade to 2.1.

[matthewdarwin]

If the blocks.log starts with 0002 or 0003 , then it is ok. starting with 0004 is error.

Ship is different where it can start with 2.0 data and then change to 2.1 format later in the file.

[spoonincode]

If the blocks.log starts with 0002 or 0003 , then it is ok

fwiw blocks.log created with early eosio versions will have 0001. Really anything other than 0004 is okay for now.

[matthewdarwin]

For better or worse, the draft documentation for 3.1 suggests to use hexdump. This seems reasonable for 3.1.

This feature can be future release.

[stephenpdiesel]

We won't be adding eosio-blocklog but instead the future work targeted for eosio util. Blocked until #765 is complete

[matthewdarwin]

This feature seems already implemented in leap-util.

[heifner]

Part of leap-util smoke-test of block-log:
./leap-util block-log smoke-test --blocks-dir dd/blocks