Restructuring Classes and add Bot.histories() to download historical market data!

Critical bug fix with api.py again. - dynamicCall(fn, [args])

Important Bug Fix - Asterisk omitted and Number of arguments mismatched

Restructuring codes in a more plausible way

Change python requirement version >= 3.7 to >= 3.6

This is v0.0.5 but first release on git whereas the package on pypi starts from v0.0.1.