Improve version builder to make it simpler to use

[EWSoftware]

The version builder plug-in needs a complete overhaul to make it more useful and simpler to use. The most important part would be to allow including version information without having to build all of the prior projects. This would likely be in the form of some sort of cached build output that could be used by the plug-in to generate the necessary version info. Related work items covered by this change (see the other work items for more details):

• SHFB should support reflection.org files as documentation sources #3
• Versioning support without access to full SHFB projects #240