Ctrl+Z removes all code in C# scripts

[abeham]

Create a new script and press Ctrl+Z.

Expected: Nothing happens.

Result: The whole script is gone.

Probably, in some way the "before" state of the script is initialized to empty.

[jkarder]

r16528: fixed ctrl+z removing all code and improved code handling in programmable operators

[jkarder]

I have also made some changes within the ProgrammableOperator and its view. The code editor that is used there creates some protected areas within the code that cannot be edited directly (e.g. the using directives) or at all (e.g. the method signature). Using directives can be added/removed by (un-)checking the respective tree nodes on the left. Previously, all using directives where shown in the code editor and adding/removing a directive was recorded in the edit history of the code editor. This lead to inconsistent states between tree view and code and also caused problems with the protected areas. Using directives are therefore not shown anymore.

[abeham]

Reviewed r16528, tested C# Script and ProgrammableAnalyzer in the GUI.

[gkronber]

r16832: merged r16528 from trunk to stable