serg changes
Merge branch 'serg' into dev
db update
final removal of MainWindow::showEditInvoiceDialog()
refactoring fix
FINAL removal of showEditInvoiceDialog()
fix date in EditInvoice
small fix
EditInvoice: supports only addition and deletion now
ClientView: fix of slots names
MainWindow: new context menus for payments and invoices tables
Proper error handling and a lot of small fixes
MainWindow: added view for PaymentIn table
added Description field to EditInvoice and table views in MainWindow, plus in queries a bit of unification