Fix activity reloading

[mrfelton]

Description:

Fix activity reloading so that it reloads existing items rather than loading a new page.

Also optimise our network, peer and balance reloads slightly so that we fetch less often and not at times when there is no need to.

Motivation and Context:

Fix #3174

How Has This Been Tested?

Manually

Types of changes:

Fix

Checklist:

• My code follows the code style of this project.
• I have reviewed and updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes where needed.
• All new and existing tests passed.
• My commits have been squashed into a concise set of changes.

[coveralls]

Coverage decreased (-0.02%) to 22.632% when pulling 59f9fd6 on mrfelton:fix/paginator into b3bf9de on LN-Zap:master.