Improve conversations loading by creating WebView on demand
Per discussion here it was decided that the best way to implement it would be by privatizing web_view field first. So commit "privatize web_view" does it by creating function proxies for web_view functions that were used outside.
Improvements of this foreach for loading 204 mails discussion, milliseconds:
Before: 10662, 10826, 11134
After : 9972, 9810, 9881Improvement: ≈10%