A bunch of shell-related fixes

Fixed: The shell now allows HTML-tags in messages.
Fixed: The shell widget's scroll pane now really scrolls to the most bottom position.
Fixed: Reorganized the order of language values in the shell i18n files.
Better file generation

Fixed: The file generation in the simulation generator now takes a lot less space.
List Files & Shell Message List Utility

Added: There's now a very simple list files ("ls") utility for listing files and directories.
Added: A shell list utility for integrating lists into shell messages so the ai can still read the vairables. The new shell list also supports colors.
Fixed: The change directory program executor is now serializable.
Cat & Text Files

Added: "cat" for displaying the contents of text files.
Added: There is now an interface which marks "text contents": TextContent.
Better Shell Messages

Fixed: The shell error messages now fit better into the whole shell context.
File Rights & Argument System Fixes

Fixed: The file rights do now work correctly with group rights.
Added: There are now letters for the file accessors.
Fixed: The argument check during the creation of a new program executor now checks required arguments correctly.
Random Fixes

Fixed: Several programs now use the easy way for getting the user of a process.
Fixed: The shell help page now has a nicer indention.
More Random Fixes

Fixed: Cat now uses the read() method for getting the file's content. That method actually checks for rights.
Fixed: Some JavaDoc issues in the new shell programs.
Removed: There are no longer unnecessary help option names in the shell i18n files.
File Rights Program

Added: There's now a program for displaying and changing file rights (called "rights").