Use CMake to build project

[sh19910711]

I suggest to use CMake to build project. It supports SDL and OpenGL.

Summary of commits

• Prepare to use cmake (>= 3.0) to build duck and gduck
• Add CMakeLists.txt
  • e.g. https://github.com/sh19910711/duck-lang/blob/ad8b6fe83b1145c41f7724980d5e6c88ff94d0e7/src/CMakeLists.txt
• Add source directory (in src/)
• Add FLAG_GDUCK switch
  • e.g. $ gcc ... -DFLAG_GDUCK -o gduck ...

$ git clone https://github.com/gregtour/duck-lang
$ cd duck-lang
$ cmake .
$ make
=> generates bin/duck and bin/gduck

I have tested the commands only on linux, and I don't touch files and directories without source directory.

[sh19910711]

I had forgotten to see language directory.

[gregtour]

I have CMake 2.8.12 so I have changed it to use cmake (>= 2.8.0). There was some restructuring I wanted to do, so I moved all of the interpreter code into a common base at /duck and moved SDLlib.h/.c to /duck/lib. Then compiler flags will enable or disable specific user libraries. Hopefully, everything should be simpler now. It's also easier to fix bugs and improve the compiler without having to merge between two directories.

[sh19910711]

nice :)