teal 0.15.0 migration

[gogonzo]

Migrate TealData into teal_data

With teal v0.15.0 all previously data classes have been deprecated and replaced by teal_data object. teal_data is now a primary teal data object for the whole teal framework. Refactor introduced breaking changes and we identify two main places where error might occur. Please visit migration pages listed below and ask for help in the comments.

1. Migrate from TealData to teal_data summarizes how to achieve this.
2. Migration from tdata to teal_data inside your teal modules summarises how to achieve this.