Learning rate policies implemented

* Momentum fixed (per connection instead of per node 😉 )
* Learning rate policies implemented

GRU improved

Scores reset to null

GATE graph nodes smaller

Fixed #14

ADD_NODE improvement

* ADD_NODE no longer removes gates
* Now, disconnect() automatically ungates the connection before
disconnecting it

Update README.md

Update README.md

MODIFY_CONNECTIONS improvement

Moved methods to subfolder

Continued work on brain.js