Some additional code cleanup

[mpnow]

Additional code cleanup

NodeConnector.cs

• Cleaned up usings.

PowerSyncData.cs

• SaveItemAsync()
  • Null out completed_by if item is marked as incomplete.
  • Write completed_by on INSERT for consistency's sake.
  • Fields rearrranged on INSERT for more logical ordering.

TodoItem.cs

• Formatting cleanup.

ListsPage.xaml.cs and TodoListPage.xaml.cs

• Refactored OnDeleteClicked() to avoid possible null reference.
• Changed variable declarations to all use implicit typing for consistency's sake.

[mpnow]

Thanks for merging my last PR!

This one doesn't have any bug fixes in it per se, so it's of course up to you whether you want to merge it in or not (or cherry pick some of the changes that you want in).

[Chriztiaan]

Thanks for merging my last PR!

This one doesn't have any bug fixes in it per se, so it's of course up to you whether you want to merge it in or not (or cherry pick some of the changes that you want in).

Cleanup and fixes are appreciated and encouraged! Thanks for spending the time to help!
I'll give it a test.

[mpnow]

@Chriztiaan Works for me!