GMake/GCC C/C++ Support

I've checked a new batch of code into Subversion with more-or-less complete support for building C/C++ projects with GMake and GCC. There are no custom build steps yet (the "less" part) but everything else should work as expected. Please give it a try! The documentation is lagging the code, and there is a lot of new stuff to document, so feel free to send questions my way. I'll start working on updated documentation this week.

At this point, 95% of the internal plumbing is now in place. The remaining work mostly involves porting the Visual Studio and other generators (see the Development Roadmap for details). With your help testing and reporting bugs I hope to have a release candidate available by the end of this month, and a final 4.0 release by the end of the year. So please grab the code and start testing!

Those of you who have been following the development of Premake will notice that this latest round of code is...different: Premake is now written mostly in Lua. Credit for the idea (or blame, depending on your point of view) goes to Thomas Harning for the suggestion. This makes Premake a bit more difficult to build, and I've added instructions in BUILD.txt to help get you started. But it also opens up all kinds of possibilities, such as the new template system, and once you've got the hang of it development is fast!

Check it out, send me feedback, and enjoy!