Similar to EquationHighlighter we need a highlighter for latex code that can be entered in LabelWidget.

General info:
http://doc.qt.io/qt-5/qtwidgets-richtext-syntaxhighlighter-example.html
src/tools/EquationSyntaxHighlighter.h/cpp

Check syntax definition in kate or in http://srchiliteqt.sourceforge.net/