Tinkering with input

I want to move keyboard input defs to the Python API. I laid the groundwork for it today.

From the JANKFILE:

- working on API endpoint `_registerInputAction`.

it will add "_py" as a suffix to the action string and register it along with other scene actions.

- Adding public Scene methods. These are on the base class with default of return `false`.

`bool Scene::registerActionInjected(int code, std::string name)` and `unregisterActionInjected`

the PythonScene (and other scenes that support injected user input) can override this method, check existing registrations, and return `true` when succeeding.

Also, upgraded to C++20 (g++ `c++2a`), mostly because I want to use map::contains.

build_linux.sh

@@ -35,7 +35,7 @@ do
         -I../../deps_linux \
         -I../../deps_linux/Python-3.11.1 \
         -I../../platform/linux \
-        --std=c++17 \
+        --std=c++2a \
         -c ../../src/$fn.cpp \
         -o ../../obj/$fn.o \
         -lm \
@@ -53,7 +53,7 @@ done
 
 # Final executable
 g++ \
-    --std=c++17 \
+    --std=c++2a \
     -I../../deps_linux \
     -I../../deps_linux/Python-3.11.1 \
     -I../../platform/linux \