Remove mandel and https://github.com/eosnetworkfoundation references in leap

[linh2931]

Changes are

• Replace mandel, Mandel, and MANDEL with corresponding leap equivalents
• Replace https://github.com/eosnetworkfoundation with https://github.com/AntelopeIO
• Bump versions for submodules in which mandel references have has been removed

[arhag]

I suggest just bringing in the remaining two submodule commit updates from #3 into here as well. I didn't understand the reasoning in the description for why they should be included as part of a separate PR.

Also, there are still mandel references in tutorials/bios-boot-tutorial/README.md. Some of them we won't be able to remove at this time like mandel-contracts. But you can do the Leap and CDT replacement.

[spoonincode]

I think this should at least be modified to include it's an implementation of Antelope. Similar to the packaging "C++ implementation of the Antelope protocol", but more prose.

[linh2931]

I suggest just bringing in the remaining two submodule commit updates from #3 into here as well. I didn't understand the reasoning in the description for why they should be included as part of a separate PR.

Also, there are still mandel references in tutorials/bios-boot-tutorial/README.md. Some of them we won't be able to remove at this time like mandel-contracts. But you can do the Leap and CDT replacement.

Sorry I missed tutorials/bios-boot-tutorial/README.md. I had trouble bringing in the two submodules. It works now. Will be bring in in this PR.

LGTM. Looking for someone to review my commits though.

[linh2931]

I pulled in latest changes, deleted my build directory, and am rebuilding from scratch. Will review your commits late tonight.

[linh2931]

Your commits look fine. My fresh build of Leap and system contracts with -DBUILD_TESTS=ON -Dleap_DIR worked. I run ctest -VV in the system contract tests directory. All tests passed: 100% tests passed, 0 tests failed out of 7