Okama 1.3.0

New features:

• rolling_window parameter in AssetList functions: index_corr(), index_beta(), tracking_error()
• index_corr() and index_rolling_corr() are combined into a single function index_corr() in the AssetList
• AssetList, Prtfolio, EfficentFrontier and EfficentFrontierReb are now sequences and has __getitem__, __iter__ methods.

Fix:

• Avoid running get_namspaces() and other aliases in init.py (this resulted in the database requests during library import)
• EfficientFrontier.plot_pair_ef() faled if inflation=False
• Tickers with dot "." like BRK.B