zcalcu: Chat & Calculator

zcalcu is a 2 in 1 chat and calculator app. This app can be swapped between a chat application and a simple calculator.

Its main features:
-Setting the app type in calculator mode by calculate default secret key "17-08-1945".
-Setting the secret key.
-Change app type and icon between calculator and chat.
-Chat a friend by a username with picture, and text.