v0.4.0

• Amount fields in function parameters calculateRates() and createSwapTransactionPayload() are refactored. Now this functions accepts numbers without decimal part. (Accepts number | Decimal)
• calculateRates() returns string value without decimal part.
• Updated Readme and expanded with more examples.
• More test cases with more examples. Covered errors cases.
• Added useful convertValueToDecimal() function with import from main.ts