Add: upgrade statistic view
BugFix: restore last selected tab in tables
Create StatusProject class
Merge pull request #15 from Lozov-Petr/model

Export.
BugFix: group adding and removing
Database import/export integration
SQLite Database Input/Output initial state
Merge pull request #16 from AlexSmirnow/develop

SQLite Database Input/Output initial state
Merge pull request #17 from ladagagina/master

Import from Excel
Merge branch 'develop' of https://github.com/Alllex/Schedule.git
Import from Excel
bug fixes
bug fixes
bug fixes
Merge pull request #18 from ladagagina/master

Bug fixes in Import