License of steem source code

Steem is open source, which means you can check the source code, compile it on your own machine and run it. How about the license model?

owner

The source code is licensed from 'Steemit, Inc., and contributors.'. So it means there is a company named 'Steemit, Inc'. and also the contributors, who is contributors?

What you can not do

From the license text, you will find that: You CAN NOT:

change the currency symbols, 'STEEM' and 'SBD' ;
add new currency symbols;
change STEEMIT_INIT_PUBLIC_KEY_STR to other value;
change the private key to start a new blockchain;

But the most important is this sentence:
"The software is not used with any forks of the Steem blockchain that are not recognized by Steemit, Inc in writing."
I think this means if we can get a permission, we can create our own forks.