add depoly contract with nep4 function for neogui (neo-project#124)

Feature/advanced transfer (neo-project#107)

* allow users to add fee to a transaction and set change address

* update dependency: Neo v2.5.2

NEP-6 (neo-project#106)

upgrade to v2.3.5

Fix neo-project#96

upgrade to v2.3.2

upgrade to 2.2.0

upgrade to 2.1.0

1. Fix neo-project#1, neo-project#21, neo-project#27, neo-project#30
2. Remember the setting of not installing the certificate
3. Save peers state to file

upgrade to 2.0.2