Created Targets file for compilation of xaml controls in same project

[aravol]

This change assumes usage as a NuGet Package. Because this is a .targets file, it will require inclusion with an existing project via addition of the following line. Note that the EmptyKeys import MUST come after the standard imoprt, or the compilation step won't be defined and the command will not execute:

<Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
<Import Project="$(SolutionDir)packages\EmptyKeysUI_Generator.*\tools\EmptyKeys.UserInterface.targets"/>

In addition, this setup presumes that .xaml files also include in compilation their corresponding .xaml.cs files since these seem to show up in the visual tree regardless. by including these, the changes caused by recreating them will also trigger Intellisense updates

[EmptyKeys]

Thanks, I will test it out :)