Addresses #357 and #365. Although not a very large change, this PR ends up touching rather a lot of code.
* Converted types `Usd`, `Leverage` and `Percent` to something that is appropriate to this application
* Created new types `Price` and `InversePrice` to use for BTC/USD exchange rate with appropriate algebraic ops implemented as well.
* Added new positive tests
* The function `daemon::model::calculate_profit()` has been changed substantially as the updated types make the existing workflow needlessly complex
* Some tests (mostly in `cfd.rs` required updating) in order to make use of the new types.
* Minor edit to `.gitignore` to avoid accidental pushing of DB to repository--should have been it's own item, added here to fix a problem that arose during this work.
NOTE:
* There may be an excess of algebraic ops implemented, some pruning may be appropriate.
Thomas Eizinger
DelicioiusHair
Mariusz Klochowicz
Daniel Karzel