Instead of child() vs concrete_child(), next_sibling() vs next_concrete_sibling(), etc,
the default is switched: child() refers to the concrete syntax tree, and named_child()
refers to the AST. Because the AST is abstract through exclusion of some nodes, the
names are clearer if the qualifier goes on the AST operations
The `pos` and `size` functions for Nodes now return TSLength structs,
which contain lengths in both characters and bytes. This is important
for knowing the number of unicode characters in a Node.
Now, the root node of a document is always a document node.
It will often have only one child node which corresponds to the grammar's
start symbol, but not always. Currently, it may have more than one child
if there are ubiquitous tokens such as comments at the beginning of the
document. In the future, it will also be possible be possible to have multiple
for the document to have multiple children if the document is partially parsed.
There's no need for a `string` function since one already
exists for Nodes.
Now the root node is always stored on the document. This
means callers of `ts_document_root_node` don't need to release
its return value.
Generated parsers no longer export a parser constructor function.
They now export an opaque Language object which can be set on
Documents directly. This way, the logic for constructing parsers
lives entirely in the runtime. The Languages are just structs which
have no load-time dependency on the runtime
My original thought was to decouple the runtime from
the LR parser generator by making TSParser a generic
interface that LR parsers implement.
I think this was more trouble than it was worth.
