[DF-1446] fix review issues in mail sender
[DF-1516] Fixed UITextFieldDelegate::TextFieldKeyPressed calling for Desktop platforms
[DF-1538] Added posibility to make UIWebView background transparent for iOS and MacOS. Fix unit tests project for iOS. Added unit test for transparent UIWebView
[DF-1538] Fixed Win32 Project
Merge branch 'to_master' into feature-testing