Sleigh Extensions

[jmg292]

Lately I've been considering the incredible potential that Sleigh has as a tool for facilitating direct hardware debugging. Before I started hacking away and building my own thing, I wanted to check in to see:

1. Is there any plan for adding flash_space as a supported space type?
2. Are there any plans for adding optional hardware pinouts to the list of possible definitions? If not, I believe I can utilize a register space definition for this
3. Is there any existing documentation on how to propose modifications to and/or safely extend the Sleigh language? If not, I'll totally just wing it

Finally, I'm in the middle of updating the Sleigh grammar definitions to antlr4 for my own use. Before opening a pull request, I wanted to check if such a contribution would be welcome, or if Ghidra will be staying on antlr3 for the foreseeable future.

Thank you for reading!