Update to miniquad-0.4

[not-fl3]

Looks like it still works!

Note that this PR does not include metal shaders, thus its just as GL-only as it was before.

miniquad-0.4 is still in alpha, but all the major changes already landed, so apart from some bugfixes - thats what we are going to have as 0.4.

I am not sure if this should be merged or not yet, but with macroquad already migrated to 0.4 - I would rather have it merged, probably with a crates version bump and maybe marked as alpha too.

[emilk]

Code looks good, but I vote we hold off on merging until miniquad 0.4 is released. Otherwise we can't release a new egui-miniquad if/when there is a new egui release (if that happens before the miniquad 0.4 release)

[vpzomtrrfrt]

so what now?

[vpzomtrrfrt]

Fails to compile on macos:

    Checking egui-miniquad v0.14.0 (/Users/colin/egui-miniquad)
error[E0061]: this method takes 2 arguments but 1 argument was supplied
   --> src/lib.rs:221:18
    |
221 |             self.set_clipboard(copied_text);
    |                  ^^^^^^^^^^^^^ ----------- an argument of type `&mut (dyn RenderingBackend + 'static)` is missing
    |
note: method defined here
   --> src/lib.rs:355:8
    |
355 |     fn set_clipboard(&mut self, _mq_ctx: &mut mq::Context, text: String) {
    |        ^^^^^^^^^^^^^            -------------------------  ------------
help: provide the argument
    |
221 |             self.set_clipboard(/* &mut (dyn RenderingBackend + 'static) */, copied_text);
    |                               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

error[E0061]: this method takes 1 argument but 0 arguments were supplied
   --> src/lib.rs:317:38
    |
317 |             if let Some(text) = self.get_clipboard() {
    |                                      ^^^^^^^^^^^^^-- an argument of type `&mut (dyn RenderingBackend + 'static)` is missing
    |
note: method defined here
   --> src/lib.rs:364:8
    |
364 |     fn get_clipboard(&mut self, _mq_ctx: &mut mq::Context) -> Option<String> {
    |        ^^^^^^^^^^^^^            -------------------------
help: provide the argument
    |
317 |             if let Some(text) = self.get_clipboard(/* &mut (dyn RenderingBackend + 'static) */) {
    |                                                   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

For more information about this error, try `rustc --explain E0061`.
error: could not compile `egui-miniquad` (lib) due to 2 previous errors