Merge pull request #19 from olga-jane/master

update from origin
Merge pull request #21 from olga-jane/master

update from origin
Merge pull request #24 from olga-jane/master

update from origin
Solution for waiting (responsive UI)

+ Added splash screen on program start.
+ Added wait screen on executing command and on creating and opening
forms through the ICommandManager binding (CommandInfo.cs).
* IUserInterface was extended.
* Splash screen and wait screen was used from DevExpress
SplashScreenManager.

Issue # 12
Solution for waiting (responsive UI)

Maked correction to names. New names:
AppWaitForm
AppSplashScreen

Issue #395
--
fixed small bug of empty guid in UnitTests - AddExternalFileTest.cs
(cannon build without it)
Merge pull request #713 from qlynn/avtc

Solution for waiting (responsive UI)