Deprecating singleton variables, use singleton getter instead

[tambien]

To disambiguate variables from class names:

• Renames Transport -> TransportClass
• Renames Destination -> DestinationClass
• Renames Draw -> DrawClass
• Renames Listener -> ListenerClass

[codecov[bot]]

Codecov Report

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

Project coverage is 98.42%. Comparing base (d0b874b) to head (63f849a).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #1233 +/- ## ======================================= Coverage 98.42% 98.42% ======================================= Files 184 184 Lines 7725 7725 Branches 680 680 ======================================= Hits 7603 7603 Misses 35 35 Partials 87 87 ```

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