BloombergDLDataProvider - check existing first (quarkfin#262)

Pdf exporter/enable image format selection (quarkfin#240)

Fix waterfall chart limits and format (quarkfin#232)

Add time convertion to DL (quarkfin#229)

Updated the signatures of Exchagne Rate Provider and Tickers Universe…

… Provider (quarkfin#219)

Adding unit tests for Bloomberg HistoricalDataProvider (quarkfin#210)

Fixed typing.Sequence imports (quarkfin#206)

Fix/improve documentation for users (quarkfin#188)

Heatmap updated (quarkfin#173)

API documentation (quarkfin#154)

* Removed dic container from api documentation
* Updated Installation prerequisites