Hotkeys customization

[GLivshits]

Please add feature to configure more hotkeys. Ctrl + Enter for submit hurts!
Also, it will be quite good to manually assign hotkeys for classification, like "1" and "0" instead of "1" and "2" for binary classification, because it's more meaningful, intuitive and provides low misslabeling rate.

[Schulzjo]

Also a hotkey for switching to next task would be nice. For example Arrow left/right or up/down

[makseq]

@Schulzjo You can use shift + up/down + enter - to switch a task in Quick view mode.

[Schulzjo]

Thx, that helps already. But I still advocate the request from GLvshits for customization. I would really like to switch tasks just with one finger in action.

[smoreface]

same as #796 and related to #208