Adding Scribe in tools

Adding the tool "Scribe"

Scribe is like a text file preprocessor similar to a HTML template file parser and generator.

It is introduced in the HIFI project to preprocess the shader source code and allow to generate several versions from a similar template file and a set of define vars. It is used like a #define mechanism for shaders allowing for different shaders implementations depdening on the platform or the features needed. It also provide a include mechanism.

Scribe produce an output file from an input starting file and possible include files. Some variables can be defined in the command line like a typical compiler preprocessor.

The output file content can be encapsulated in a c header file as a const variable char[]. THis is what we will use to add the shaders to the compilation in upcoming PR.

- also added some usefull comments in Transform.h

- TODO, we need a Documentation page on Readme.io about Scribe
curious, why does `block` need to wrapped in parentheses here?