Provide Build Script, Minor Performance Improvement for the X3D Output, Add Emscripten as a target

[mmha]

Hey :)

Summary of my commits:

• cb8012d: Make the code compilable and installable using CMake. Additionally, I can confirm the code works with gcc and clang
• bb330e0: std::endl flushes the buffer of the stream - \n does not. This should improve the performance a little bit
• 41f41fb: I added support for emscripten to the build scripts and tested basic functionality with it using the webdemo.html stub, which can load tgen either as asm.js or WebAssembly.

My idea behind the emscripten target is that we could write a small web application that preprocesses a glTF file using the proposed strategies, displays them and makes them available to download, while keeping the reference implementation in C++.

There are more commits that actually add functionality to the library following shortly. I don't consider them ready quite yet.

[mlimper]

Hey, thanks. just did a quick review. Apart from the obvious, necessary bugfixes (thanks for that!):

I really like the idea to have a minimalistic CPP implementation, consisting of only one header and one CPP file (not necessarily C++11). I didn't intend to make this a real library, that's actually changing the scope of the project.

What about building a library plus applications in a separate project? These CPP and H files could then be easily integrated there as a very simple "3rdParty" component (also via CMake, if wanted). This way people could easily decide what they want for their application. The new project could include advanced lib functionality (such as Emscripten bindings, different build options etc.) and a main application as demo, the Web app, etc.