scripting-api enable search, enable left hand side treeview, correct code style

Use the modern doxygen look. Icon for "C" for classes. Make code examples readable. Source code is now indented.

See https://drive.google.com/file/d/1cMuaWF2HtHOCO6pIBDujIwn12vsofILr versus https://apps.kde.org/education/kig/scripting-api