added notes on describe() and XML docs
History revisited: _historyIndex remains on the same place if entry has been redone. Use case: Replaying of previous input. Example:

Prepared autocompletion for arguments of shell commands.
Completion of CMD arguments: Directories
Tests:
>>> cd[TAB]
>>> cd \[Tab]
Read background and foreground colors from the shell and modify the standard color configuration accordingly. This avoids nasty appearance if background is not black.
Added some remarks on the purpose of this namespace. Will also be used for testing the support of XML docs.
Autocompletion of file args. Test "cp" with completion of 2 arguments.
Make sure that the new suggestions for autocompletion before the first full stop appear at most once by using a set
Damned: Don't want to use sets where not actually required. Some suggestions are not comparable

This reverts commit 3cab49092f60513d3b6e4e8276ed2b0b571c0160.
do not unnecessarily recompute list of suggestions
Autocompletion of type names for shell commands work
Finished with completion of shell commands args. now, booish should be great for exploring the opportunities of .NET assemblies.