Please update requirement.txt and submodule

[JamieOw119]

In 'gantool/blocks.py', tf.nn.conv1d_transpose does not exist in TensorFlow 1.13.2，when I update TensorFlow to 1.15.X，program works.
And there are something wrong about submodule, after running 'git submodule update --init --recursive'，the obtained version of tfnntool is inconsistent with the version pointed to by the GitHub webpage —— the content of 'tfnntools/nnsystems.py' is different.