Add ApprovedExeForElevation element, IBootstrapperEngine::LaunchApprovedExe, IBootstrapperApplication::OnLaunchApprovedExeBegin, IBootstrapperApplication::OnLaunchApprovedExeCompleted, and enable WixStdBA to use them.
Format the arguments sent to LaunchApprovedExe, and address feedback.
Merge branch 'NetFxExtension-4.5.2-support' of git://github.com/gordonmcshane/wix3 into develop
Merge branch 'develop' of https://github.com/wixtoolset/wix3 into develop
Merge branch 'testfixes' of git://github.com/heaths/wix3 into develop
Merge branch 'develop' of https://github.com/wixtoolset/wix3 into develop
Merge branch 'relbundles' of git://github.com/heaths/wix3 into develop
Merge branch 'develop' of https://github.com/wixtoolset/wix3 into develop
Merge branch 'feat3249rebased' of git://github.com/rseanhall/wix3 into develop

Conflicts:
	History.md