introduce Greek and Latin symbols

[zuevval]

see article, point 11

• add caption on top of each symbol in Practice and in Materials Browser
• add deck with Greek symbols
• add deck with Latin symbols

[winter-yuki]

Maybe do not add new symbols to deck All decks?

[zuevval]

Then it must be renamed. Or include a variable part. Or something. I will think about it.

[zuevval]

Maybe do not add new symbols to deck All decks?

@winter-yuki I have anticipated this problem, that's why I wanted to convert list of decks into settings screens with a list with checkboxes. But of course this all is still a subject to careful consideration.

[winter-yuki]

Decks menu's purpose is to choose a particular theme to work with. This problem should be solved on the level above: checkboxes that form decks list itself and All cards deck at the same time. Enough solution for this issue should be not to include new cards in the All cards deck. Also, an issue for such checkboxes in settings should be created.

[zuevval]

Ok, as a temporary workaround it might work well