Fix uninitialized data returned from digest_guid
Add util.deep_clone_table to do just that.
Visual Studio generator improvements

Allow external projects to be included in solution files.
Allow variant names to be remapped to MSVC friendly names.
Add fancy VS2012 generation example.

Fixes GH-183
small buildfix for my local machine
enhanced error messages for file globbing
msvc tools: pass CPPDEFS along to rc.exe as defines
Fixed missing default var for C# tools.
XCode project generation fixes.

Fix bad characters in GUIDs.
Fix config matching was matching "macosx"; use SupportHosts and
DefaultOnHost instead to match tool.

Still not loading in Xcode but data looks better..
MSVC generation fixes

- Fix .a, .o files appears when run on Linux/Mac OS X
- Fix ExternalLibrary units crashed the generator

Closes GH-187
Merge branch 'master' of https://github.com/deplinenoise/tundra