refactor(TestMACD): remove duplicated unit test

refactor(SlowStochastic): convert class to a function

refactor(CCI): change CCI class to a function

docs(README): add badge and EMA call in example

BREAKING CHANGES(MovingAverage): remove class and transform all metho…

…ds into functions

fix(DMI): fix `source` variable not found

fix(DMI): fix `source` variable not found

fix: fix utils import

feat: add Ichimoku class

docs: update readme