Add gdscript2rst scripts

AT this stage you should have a folder structure something like this:

.
├── _build
├── _static
│   └── css
│       └── custom.css
├── _templates
├── conf.py
├── index.rst
├── make.bat
└── Makefile

We now need to add the gdscipt files that will extract the information from the Godot project and the files that will convert this information to .rst files.

Follow the instructions for installing these found at Script files

Once the script files are installed you have a folder structure like:

.
├── _build
├── godot-scripts
│   ├── Collector.gd
│   ├── ReferenceCollectorCLI.gd
│   └── ReferenceCollector.gd
├── _static
│   └── css
│       └── custom.css
├── _templates
├── conf.py
├── generate_reference
├── generate_reference.bat
├── index.rst
├── make.bat
└── Makefile