I'm sure there are still some warts, but interface declaration now works
for spir-v and a real vertex shader can be compiled (albeit one that
doesn't use matrices).
I don't know why I thought it was a good idea to make sy_var context
dependent. Renaming sy_var to sy_def makes it a little easier to know to
use the def field, too.
Each interface type (in, out, uniform etc) gets its own namespace, and
non-instanced blocks get a namespace (their block name) within the
interface namespace.
The defs for the block members are currently "allocated" to be at offset
-1, but the idea is to allow layout qualifiers to know if the member has
already been located.
Attributes seem appropriate as GLSL's qualifiers affect variables rather
than types (since there's no typedef).
Not much is done with the attributes yet other than some basic error
checking (duplicates of non-layout attributes) and debug output, but
most (if not all) declarations get to the declaration code with
attributes intact.
Now parameters can be declared `const`, `@in`, `@out`, `@inout`. `@in`
is redundant as it's the default, but I guess it's nice for
self-documenting code. `const` marks the parameter as read-only in the
function, `@out` and `@inout` allow the parameter to pass the value back
out (by copy), but `@out` does not initialize the parameter before
calling and returning without setting an `@out` parameter is an error
(but unfortunately, currently detected only when optimizing).
Unfortunately, it seems to have broken (only!) v6 progs when optimizing
as the second parameter gets optimized out.
There's no direct support for namespaces in Ruamoko yet, nor even in
qfcc, but glsl's blocks bring in a bit of foundation for them, even the
concept of "using" (for blocks with no instance name).
The members don't get locations allocated to them yet, but
fstrianglest.vert compiles and links correctly otherwise.
Also, there's no error checking yet.
