Implement graphs #43
Description
TODO:
- improve rendering performance through 8 simultaneous threads, instead of coroutines
- adjust all graph characteristics, especially colors, via xml
- smooth graph scaling
- graph in a calculator fragment
- expression in a graph fragment
- sign axes (x, y)
- make numbers in the middle of the coordinate grid
- fix overlapping of numbers at any scaling
- disable too small scaling
- error with number "e-7"