Fix ProjectInstance.ToolsVersion, never returned valid value.
ProjectInstance never had valid ToolsVersion because ProjectRootElement holds "", not null(!) for default value.
implement MetadataAccessExpression evaluate methods.
Make use of XBUILD_FRAMEWORK_FOLDERS_PATH in GetReferenceAssemblyPaths task and make it testable importing common targets.
Evaluate Target Condition too.
For ItemType-less metadata expression, apply all items in the project.
For Condition, "yes", "no", "on" and "off" are also treated as valid boolean...
Handle target Inputs and Outputs so that extra targets can be skipped. Add some value convert (for task property) tests.
fix test file name.
do not try to evaluate and set non-required and empty Task parameter for ITask instance.