* Remove unused petgraph dependency from glsl-out

* Emit std430 layout qualifiers for storage buffers

Ensure that each distinct type occurs only once in `Module::types`, so that we
can use `Eq` on `Type` or `TypeInner` for type equivalence, without being
confused by differing `Handle<Type>` values that point to identical types.

This removes a number of duplicate types from the ir snapshots.

Fixes #1385.

* [spv-in] New two pass parser based

* [spv-in] Allow expressions defined in dominant block in different scopes

* Make the patch non breaking

* [spv-in] Allow scope transfers in phi instructions

* [spv-in] Remove unused stuff

* [spv-in] Handle switch merges as breaks

* Remove no longer needed stuff

* Revert some changes to prepare to merge

* Remove dead code

* Don't spill into local if in scope

* [spv-in] Documentation, comments, some renaming for clarity.

* Address comments

Co-authored-by: Jim Blandy <jimb@red-bean.com>

* Implement lexing for all WGSL number literal types

* Move number literal test cases

* Adjust tests to match WGSL spec on number literals

Suffixes are not type names and currently only a plain `u` is supported
for uints. More specifically, `i` and `f` suffixes or suffixes with
widths in bits like `u32` are not supported at the moment.

* Add more tests for invalid number literal suffixes

* Replace code too new for Rust 1.43

* Implement parsing for hexadecimal integers

* Switch to enum number types, and Bytes for width

* Check for negative and leading zeros in int literals

* Implement parsing of hex floats with hexf-parse

* Update error message tests

* Update snapshot test output files

* Clean up lexer state machine code

* Clean up unexpected token error code

* Move number literal parsing to own submodule

* Proof of concept for "span" feature, with WGSL parsing augmented.

* Review:

1) add_span was actually a bad idea, make it set_span and add
set_span_if_unknown too.
2) panics on getting/setting span for invalid handles.
3) only set span for constants with a name
4) don't overwrite spans for types.

* Added spans to blocks & more expressions getting spans in frontends.

Definitely the shotgunny type of commit, but what can you do. The design
I went with made spans mandatory to specify, so I had to go and wire
them through wherever I could.

* Moved Block to a separate module, +clippy

* More spans for types in GLSL.

* Remove pointless body method.

* Make Arena interface require spans.

Another shotgun commit, oh boy...

* Fix tests.

My loathsome habit to "quickly fix things along the way" made a lot of
extra work for me here, having to fix my "fixes" for WGSL parser.

* Rustfmt + clippy.

* Fix compile-errors with span feature enabled.

* Nuked set_span* from orbit. Deleting code feels great!

* Code review - move feature flags inside functions.

* Fix build with "deserialize" feature enabled.

For debugging. Maybe there's a way to do it for all tests,
not sure...

Naga is now a workspace with `naga` and `cli` as its two members. The default
package for cargo commands is `cli`, so that `cargo run` will just run the CLI.

However, this has a few unexpected consequences:

- Now `cargo test` will just try to run `cli`'s tests, of which there are none.
  Adding `"."` to the `default-members` list in the workspace's `Cargo.toml`
  seems to fix this, without breaking `cargo run`.

- Even with `"."` added to `default-members`, `cargo test` will build `naga` by
  default with the features requested for it in `cli/Cargo.toml`: all the front
  and back ends, but no `serialize` or `deserialize`. This means that our CI job
  meant to verify no-feature builds isn't doing that job any more. We need to
  pass `--package naga` to `cargo test` to make it test naga directly.

* move bin/naga.rs to a separate crate

* enable all shader languages for naga binary

* [naga-cli] add env logger

* [naga-cli] remove unneccessary code

* [naga-cli]enable glsl-validate feature

* move naga-cli to cli, add trailing newline

* remove commented env_logger dependency

- added constructs
- added loop detection
- some logic from Tint borrowed for selection constructs

* Add hlsl-out feature

* Integrate hlsl-out with snapshots

* Add snapshot

* [glsl-in] Add initial support for glslpp-rs

* [glsl-in] Add remaining Punct mappings

Fix some tests.

* [glsl-in] Add basic error handling for glslpp-rs

* [glsl-in] Fix clippy issues

* [glsl.in] Add pp-rs floats

* [glsl-in] Remove old lex and preprocessor

* [glsl-in] Improve lexer token code

* [glsl-in] Rename lex_pp > lex

Also LexerPP > Lexer

* [glsl-in] glslpp-rs review feedback

* [glsl-in] Use rev for pp-rs dep

* [glsl-in] Parse on lexer err

Moved the global writing part to it's own function
Merged the texture and the global loop
Applied some suggestions from kvark
Added a topological sorting of the call graph before writing
Removed the struct block loop and now every struct is written
Organized the main backend file a bit