-debugMode: Last build results functionality

[sayedihashimi]

When Invoke-MSBuild is called with -debugMode we should keep the last build result. When Invoke-MSBuild is called again (with or without -debugMode) we should re-set that value to either the new result or null.

After we save this value we can create the following cmdlets. These would be an alternative to assigning the result to a var and accessing via instance methods.

cmdlets / adv functions to create

• Eval-MSBuildProp
• Eval-MSBuildItem
• Expand-MSBuildString
• Get-MSBuildItems
• Set-MSBuildProperty
• Remove-MSBuildProperty
• Remove-MSBuildItem
• Save-MSBuildProject

Note: We should ensure that these are not confused with the existing "construction" related advanced functions.

We should be able to pipe the project to these cmdlets as well. Using the last build result should be the default.