Merge Carl's preprocessor into the glcpp subdirectory.

glcpp/README

@@ -0,0 +1,30 @@
+glcpp -- GLSL "C" preprocessor
+
+This is a simple preprocessor designed to provide the preprocessing
+needs of the GLSL language. The requirements for this preprocessor are
+specified in the GLSL 1.30 specification availble from:
+
+http://www.opengl.org/registry/doc/GLSLangSpec.Full.1.30.08.pdf
+
+This specification is not precise on some semantics, (for example,
+#define and #if), defining these merely "as is standard for C++
+preprocessors". To fill in these details, I've been using the C99
+standard (for which I had a convenient copy) as available from:
+
+http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf
+
+Known limitations
+-----------------
+Macro invocations cannot include embedded newlines.
+
+The __LINE__, __FILE__, and __VERSION__ macros are not yet supported.
+
+The argument of the 'defined' operator cannot yet include enclosing
+parentheses.
+
+The #error, #pragma, #extension, #version, and #line macros are not
+yet supported.
+
+A file that ends with a function-like macro name as the last
+non-whitespace token will result in a parse error, (where it should be
+passed through as is).