Makefile: add test-server target.
test: add a textarea to the test HTML file for quick testing
test: the HTML sandbox currently only has to read, not parse
read: start moving matching logic into Rule impls
read: move terminal matching logic into Rule impls
read: move primitive matching logic into Rule impl
read: remove type switch from interface
read: change the return type of r5js.bnf.Rule#match
read: move sequence matching to Rule impl
read: remove dead code path
read: move alternation matching to Rule impl
read: remove no-longer-used state and methods
read: remove the grammar definition to a new gramamr file
read: complete transition to Rule-driven reading
bnf: remove no-longer-used r5js.bnf.Rule#getName()
bnf: separate impl classes for one vs. repeated matching
bnf: unify One_ and OneTerminal_, simplifying the grammar DSL
bnf: not all rules need to be named. break out subinterface.