Add helpers for zooming an app using Ctrl+Plus and Ctrl+Minus (#2239)

* Using tracing-subscriber in hello_world example

* Add Key::Plus/Minus/Equals

* Warn if failing to guess OS from User-Agent

* Remove jitter when using Context::set_pixels_per_point

* Demo app: zoom in/out using ⌘+ and ⌘-

* Demo app: make backend panel GUI scale slider better

* Optimize debug builds a bit

* typo

* Update changelog

* Add helper module `egui::gui_zoom` for zooming an app

* Better names, and update changelog

* Combine Plus and Equals keys

* Last fix

* Fix docs

Cargo.toml

@@ -15,9 +15,6 @@ members = [
     "examples/*",
 ]
 
-[profile.dev]
-split-debuginfo = "unpacked" # faster debug builds on mac
-
 [profile.release]
 # lto = true # VERY slightly smaller wasm
 # opt-level = 's' # 10-20% smaller wasm compared to `opt-level = 3`
@@ -26,3 +23,12 @@ opt-level = 2 # fast and small wasm, basically same as `opt-level = 's'`
 # opt-level = 3 # unecessarily large wasm for no performance gain
 
 # debug = true # include debug symbols, useful when profiling wasm
+
+
+[profile.dev]
+split-debuginfo = "unpacked" # faster debug builds on mac
+opt-level = 1                # Make debug builds run faster
+
+# Optimize all dependencies even in debug builds (does not affect workspace packages):
+[profile.dev.package."*"]
+opt-level = 2