A tool to add special characters and diacritics to text.
Also added a new button type ve.ui.GroupButtonWidget that includes a
group of PushButtonWidget objects and returna the individual button's
value upon click
Wikis can edit <visualeditor-specialcharinspector-characterlist-insert>,
a JSON string, to include their own desird special characters to insert
through the tool.
Bug: 50296
Change-Id: I26d1f437feef1c8b61ed3be5f74ef524b33baf49
