The User object only stores group names

Remove: The User object no longer stores group objects because they would have needed to be mapped to the group configuration file.
File system access cleanup

Fix: Move the global file system access methods from FileUtils to FileSystemModule.
Fix: The local file system access methods throw an IllegalArgumentException instead of an IllegalStateException if the input file path isn't valid.
Split the process launch function into multiple executors

Fix: The LAUNCH function of processes was too big, so it is split into multiple smaller function executors.
Add common files constants

Add: The common files class contains mountpoints and file paths which are commonly used (e.g. system configs).
Fix minor issues in Process

Remove: Processes are no longer non-existing syscall invokers.
Fix: Some minor JavaDoc and ordering issues.
Process module & bootstrap + shutdown

Add: The process module handles the root process of a system.
Remove: The process manager is no longer required.
Add: A basic bootstrap and shutdown system which also replaces the kernel program.
Remove: The kernel program is no longer required.
Remove the dead class MountException

Remove: The MountException wasn't used anywhere.
Move SET_RUNNING executors to os modules

Fix: The functionality of the SET_RUNNING method in the OperatingSystem class is moved to the different os modules. The actual SET_RUNNING method in OperatingSystem only calls those module methods. For standardization of the module method, every os module extends the OSModule class.
Move the os modules into correct packages

Fix: The location of the os module is based on their function. For example, the file system module is located in the .world.comp.file package instead of the .world.comp.os package.
Replace NetworkManager with (empty) NetworkModule

Add: The NetworkModule class is a normal operating system module which will eventually take care of sending, receiving and handling packets, as well as establishing connections. However, this functionality won't be implemented before the new network system is up and running. The module class is currently empty.
Remove: The old NetworkManager because it is no longer required.
Overhaul the session class

Fix: Move the old SessionProgram ckass to the .world.comp.os package and rename it to just session.
Add: The session reads the session user from the user configuration file.
Add: The session checks a supplied password if there is a parent session and it is not a root session.
Fix some minor issues (housekeeping)

Fix: Some very minor formatting or javadoc issues (mainly formatting).
Breaking: Remove all old programs & session stuff

Remove: The old programs and sessions were created using the old program system which will be deprecated soon. We decided to remove all these old programs because the news system takes a totally different approach. However, some of the classes this commit removes could be used later on for the new display system.
Remove old artifacts

Remove: Some artifacts left about by the old programs. They are no longer required as they are replaced already.
Fix the main class

Fix: Some problems in the main class which were overlooked for quite some time.
Fix: Some formatting issues in the main class.