=head2 Bootstrapping the Lua API interface
The file F<protos> contains C prototypes for Lua routines which may
throw errors via C<lua_error()>. The Perl interface code for these is
generated from templates. All other Perl interfaces are hand crafted.
Lua API routines which can throw errors have to be sandboxed so that the
Perl runtime environment isn't corrupted. This is done by creating C
wrappers designed to be invoked via Lua's protected call mechanism.
If the API routine throws and error it is caught and translated into a Perl
exception.
The wrappers are generated in two steps.
F<utils/pproto> parses the C prototypes in F<protos> and generates a YAML
database containing the parsed result (F<protos.yml>). It also adds
any "hints" to the contained in F<proto_hints.yml>.
F<utils/genxs> reads F<protos.yml>, F<wrap_xs.tpl>, and F<xs_xs.tpl>
and generates F<wrap.h> and F<xs.h>, which are included by F<API.xs>.
F<wrap_xs.tpl> and F<xs_xs.tpl> are B<Template::Toolkit> formatted
code templates. F<xs.h> contains the Perl XS interface code, F<wrap.h>
contains the C wrappers for the Lua API routines.
At present the above scripts are invoked manually.