This reverts commit 22331f62.

Correct some grammar on documentation

also add more tests to cover non-prefixed string import

also covered by test

Added more detailed contracts to better understand Coconut's zk-SNARKS flow.

still problems with windows executable

also added more tests for zencode_data, normalised the syntax of ECDH
and ECDSA and completed the documentation

return 0 on success, 1 if error (as shell script default)
also removed old dockerfile