missed the return operator with IsAllowProcessing for Deferred PRE

/Without returned we can't stop the increasing depth for some DTE commands
Added the new predefined operations & changed default value(as false) for abortOnFirstError

We have a some ambiguity with predefined "Rebuild Solution", because we have 2 commands:

* ({"Build.Cancel", "Build.RebuildSolution"}, "Rebuild Solution")

The "RebuildSolution" will never be executed by default if the Build.Cancel not available at the current time. Therefore this may confuse for user..

* New operations:
* * "Run all Unit-Tests"
* * "Debug all Unit-Tests"
Merge branch 'develop'
public release

* FIXED: Crashes, if solution contains the unloaded projects (Thanks for testing: Rafael Cossovan)
* FIXED: Resolved the loop problem for recursive DTE-commands.
* CHANGED: "Abort operations on first error" - Changed default value on false for new configurations.