Hotkeys, tooltips behaviour change and some other improvements

- Added hotkeys for couple of common operations: Open new tab (Ctrl+T),
Close current tab (Ctrl+W). Also pressing Ctrl+Tab now allows for
correct cycling through opened tabs without triggering "add" button.
- Tooltips in table views now get displayed at cell's lower right corner
and activated only if cell text is clipped by a column border.
- Pressing Enter key on date picker fields now applies release table
filter.