Restructure the whole project using subdirs template, add unit tests stub
RegisterUser function cleanup and parameters' map implementation
Update of registration logic and graphical interface for the registration Page
Settings initializer refactoring
Major API functions overhaul; enums, new functions, asynchrony
Create remaining API functions' stubs, fix memory leak on QNetworkReply
Revise pay() functions and add appropriate comments
Refactor JSON processing

Function getJsonOutcomeObject has been changed to getJsonOutcomeValue
since some success replies and most error replies contain a json array
instead of a json object; more general approach is needed.
QJsonValue::toObject() and QJsonValue::toArray() are called
in processing functions.
Revise login() functions and add appropriate comments
Fix improper signal name, ensure const-correctness
QStringLiterals in Core::getJsonOutcomeValue
QStringLiterals in Core::receiveReply
QStringLiterals in Login functions
Revise generateCaptcha() functions and add appropriate comments
Fix minor typos and style errors
Revise getUserInfo() functions and add appropriate comments; fix a "Qstring" bug
Add comments to sendMessage() request
Add comments to getCurrencyRates() request
Add comments to getUserInfo() request
Add comments to editUser() request