Added support for context menu in WPF
Added support for context menu parameters. All supports new spell check feature #222
Added support for context menu in WPF
Added support for dictionary suggestions in the context menu  #222
Added support for new Browser.ReplaceMisspelling to allow you to replace the currently misspelled word with a new one
Added Browser.AddWordToDictionary() support, to allow adding custom word to the spell checker dictionary
Added new AddWordToDictionary to WinForms as well (previously only in WPF)
Cleanup OnBeforeContextMenu code
Merge branch 'feature/wpf-contextmenu' into feature/2171-contextmenu-parameters

Conflicts:
	CefSharp.Core/Internals/ClientAdapter.cpp