Treesitter parser for Norg

This repository is an attempt at building on the initial tree-sitter-norg parser in order to both decrease the size and increase the speed of the parser.

Upgrades from the old parser include:

Grammar-based -- the old parser almost entirely relied on a C++ scanner.cc, which hindered error handling and parsing efficiency.
Lightweight - the parser weights 4x less than the first generation parser, greatly thanks to a smarter design and a heavier reliance on the grammar.

Thanks to its smaller size, the parser should be embeddable almost anywhere.