Test Suite adjustments to work with changes

The TestHostUserInterface derives from LocalHostUserInterface now in order to make
more elaborate functions as the Prompt() function of the LocalHostUSerInterface better testable.
Therefore, the TestHostUserInterface overrides all ReadXXX and WriteXXX functions as all other
functions will depend on those now.

Also, it's now internally optional to add read data to the history. Currently on non-Windows systems
getline.cs is used as a cmdline interface which also supports a very basic history. However, simple reads
shouldn't end up there.
Tests & bugs fixed for interactive cmdlet parameter gathering