Remove LookAhead Bias

[wescules]

Problem this change Fixes:

1. [Most important] Removes the Lookahead Bias in fvg() and swing_highs_lows() from the old implementation. The old implementation is cheating and cannot be used in real live trading since it looks into the future
2. Added SwingMethodEvaluator to swing_highs_lows(). Users can experiment with which evaluator results in the most profits!
3. Cleaned up some code

Quality of life fixes:

1. added loading bar while running smc_test.py because it takes like 10 mins on my laptop :(
2. improved performance of swing_highs_lows()
3. improved quality of the generated gif

Note: Thank you @joshyattridge this library is dope. I'm glad to help.

[joshyattridge]

Hello @wescules,
Thank you for your contribution to this project, I want to be able to merge these additions but do you think you can change the unit tests so they pass.
Thank you,
Josh