Introduce NanoAddress type

[luxbe]

As groundwork to work on the Nano Name Service integration, I first introduced a basic NanoAddress type which represents valid Nano address in the form of nano_.+. I replaced the references to addresses from string to NanoAddress which affected more files than I initially expected.

TODO:

• [x] validate addresses in methods (e.g. wallet.send)
• [x] ~stricter validation of addresses~
  • ~currently, any string starting with nano_ is a considered a valid NanoAddress. This could be tightened to check for the length of the string~
  • Commit #35fb3f6 introduces stricter validation of nano_ addresses with help of the nanocurrency library
• [x] fix README.me
  • there are some differences between the interfaces referenced in the README and the actual implementation - for example ConfirmationFilter includes from, which does not exist in the actual interface.

In the next step I plan to add a NanoUsername type to resolve actual usernames - however this is not part of this PR.

Let me know what you think of the changes and also how I should proceed with the TODOs!

Closes #1

[luxbe]

Another possible improvement would be to turn NanoAddress into its own class with a constructor, that could check the input string for validity

[tgerboui]

The changes seems goods to me for now, you can continue on this path.

Good catch about the from in the documentation, don't worry about this I will fix this in another PR, this is not the scope of this one. Otherwise you TODO is appropriate for this feature.

I'm not sure about the NanoAddress class, I think it will complicate the code and confused the user. Let keep it simple. But if you have a strong argument for using it let me know.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (950505d) to head (b7bd5c6).

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 25 29 +4 Lines 402 435 +33 Branches 66 76 +10 ========================================= + Hits 402 435 +33 ```

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[luxbe]

Should I also update the version to 1.3.0?

[tgerboui]

Should I also update the version to 1.3.0?

No don't worry, I will create a PR for this I think.

I'm not sure about the versioning protocol for now.

[tgerboui]

While reviewing, I saw that the change method of the wallet is not in the documentation of the README, I will create an issue.