v0.4.0

This version contains breaking changes.

What's Changed

• added types and a tx file for tx related functions by @logicalmechanism in #45
• Refactor total token amount by @logicalmechanism in #46
• did a lot of small refactorings, check changelog by @logicalmechanism in #47
• candidate for v0.4.0 by @logicalmechanism in #44

Full Changelog: v0.3.4...v0.4.0