Issue 101: Improve doc readability

[cedelavergne-ledger]

Update code readability:

• Add inline comment for functions description
• Minor code optimization to ease readability
  • Remove useless parameter for ui_info
  • Remove useless functions gpg_init_ux and io_seproxyhal_display
  • Add constant definition
  • Unique function app_reset instead of duplicate code
• Replace multiple if by switch/case
• Update version to 2.2.2
• Fix pytools ECC key attribute name

This fixes #101

Checklist

• App update process has been followed
• Target branch is develop
• Application version has been bumped

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 27.01%. Comparing base (400ff19) to head (2ec0a05).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #104   +/-   ##
========================================
  Coverage    27.01%   27.01%           
========================================
  Files            1        1           
  Lines          211      211           
========================================
  Hits            57       57           
  Misses         154      154           

Flag	Coverage Δ
unittests	27.01% <ø> (ø)

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