new request parsing/handling, name request caching, ``fontdbutil`` -> ``luaotfload-tool``

addresses this item: https://github.com/lualatex/luaotfload/issues/14

and installs the new syntax parser (the old one is still there for reference in ``luaotfload-features.lua`` and can be quickly installed when testing, but it will vanish once we’re confident the new one does the job well)