Improve the experience of using muxed account.

[overcat]

No description provided.

[codecov]

Codecov Report

Merging #311 into dev will increase coverage by 0.00%.
The diff coverage is 99.19%.

@@           Coverage Diff            @@
##              dev     #311    +/-   ##
========================================
  Coverage   99.06%   99.07%            
========================================
  Files         114      116     +2     
  Lines        5220     5485   +265     
========================================
+ Hits         5171     5434   +263     
- Misses         49       51     +2     

Flag	Coverage Δ
#unittests	99.07% <99.19%> (+<0.01%)	⬆️

Impacted Files	Coverage Δ
stellar_sdk/helpers.py	100.00% <ø> (ø)
stellar_sdk/sep/stellar_web_authentication.py	95.74% <ø> (ø)
stellar_sdk/fee_bump_transaction.py	97.05% <83.33%> (+0.28%)	⬆️
stellar_sdk/muxed_account.py	96.07% <96.07%> (ø)
stellar_sdk/__init__.py	100.00% <100.00%> (ø)
stellar_sdk/account.py	100.00% <100.00%> (ø)
stellar_sdk/operation/account_merge.py	100.00% <100.00%> (ø)
stellar_sdk/operation/allow_trust.py	100.00% <100.00%> (ø)
stellar_sdk/operation/bump_sequence.py	100.00% <100.00%> (ø)
stellar_sdk/operation/change_trust.py	100.00% <100.00%> (ø)
... and 26 more

[overcat]

Hi @abuiles, do you think it is worth adding the MuxedAccount class to js-stellar-base? I would love to hear your opinion.