TreeIt: Display the content of directories as a tree

This class can be used to display the contents of a directory as a collapsible tree.

It scans a given directory recursively to retrieve the list of files and sub-directories. It can use caching to avoid the overhead of scanning the directory again in subsequent accesses. Some files and directories may be excluded from scanning.

The class can display the directory structure as nested HTML nodes for each directory that is found. The directory entries may be collapsible or not.

Each directory and file is represented by its name and an icon according to the file type.