2.0.0 Refactored codebase

First and biggest change: a massive code refactoring to move all transaction types into separate classes.

Additional changes:

• Tax rate lookup now uses built-in system
• Tax rate URI now in error message if there is a failure on non-Terra chains
• IBC routes are now dynamically generated
• USTC can now be used as a swap route option if OSMO is not available
• IBC routes displayed in transaction summary
• Disabled native Terra coins are now filtered out
• Lots and lots of Osmosis swap options added (too many to list, see README.md)
• Osmosis wallet addresses can now be created in configure_wallet.py
• Final sent and received amounts displayed in summary
• Constants file tidied up, less keyword duplication
• Liquidity availability checked before a pool is used
• Price lookups are now a single request and cached for duration of script
• Balances report values made consistent - no more zero values
• Precision calculation improved, now dynamically generated
• Governance options now available via governance.py
• Voting on proposals now available