Continue PSBT work

[JAGADISHSUNILPEDNEKAR]

PSBT (BIP-174) Implementation

This PR implements support for Partially Signed Bitcoin Transactions (PSBT) as defined in BIP-174.

Background

This is a continuation of my previous work on PR #118 which was accidentally closed. I've created this new PR containing the same implementation with all the feedback addressed from the previous PR.

Implementation Details

• Added psbt.py module with full PSBT creation, parsing, and manipulation support
• Implemented PSBT serialization and deserialization
• Added support for combining and finalizing PSBTs
• Included utility functions for working with PSBTs

Testing

• Added comprehensive test suite for PSBT functionality
• All tests are passing and maintain compatibility with existing code

Examples

Included example scripts demonstrating:

• Creating PSBTs
• Signing PSBTs
• Combining multiple PSBTs
• Finalizing PSBTs

Documentation

• Added documentation for the PSBT module
• Updated existing documentation where relevant

I appreciate your review and feedback. Please let me know if any further changes are needed.

[JAGADISHSUNILPEDNEKAR]

#131

[karask]

This is probably not needed anymore. Correct?

[JAGADISHSUNILPEDNEKAR]

Yes I will close it