Naming and coding style convention, new linter tool. (#945)

* Makefile, Scripts: new linter
* About: remove ID from IC
* Firmware: remove double define for DIVC/DIVR
* Scripts: check folder names too. Docker: replace syntax check with make lint.
* Reformat Sources and Migrate to new file naming convention
* Docker: symlink clang-format-12 to clang-format
* Add coding style guide

lib/app-template/app_template.cpp

@@ -0,0 +1,102 @@
+#include "app_template.h"
+
+/*
+To use this example you need to rename
+AppExampleState - class to hold app state
+AppExampleEvent - class to hold app event
+AppExample      - app class
+app_cpp_example - function that launch app
+*/
+
+// event enumeration type
+typedef uint8_t event_t;
+
+// app state class
+class AppExampleState {
+public:
+    // state data
+    uint8_t example_data;
+
+    // state initializer
+    AppExampleState() {
+        example_data = 0;
+    }
+};
+
+// app events class
+class AppExampleEvent {
+public:
+    // events enum
+    static const event_t EventTypeTick = 0;
+    static const event_t EventTypeKey = 1;
+
+    // payload
+    union {
+        InputEvent input;
+    } value;
+
+    // event type
+    event_t type;
+};
+
+// our app derived from base AppTemplate class
+// with template variables <state, events>
+class AppExample : public AppTemplate<AppExampleState, AppExampleEvent> {
+public:
+    uint8_t run();
+    void render(Canvas* canvas);
+};
+
+// start app
+uint8_t AppExample::run() {
+    // here we dont need to acquire or release state
+    // because before we call app_ready our application is "single threaded"
+    state.example_data = 12;
+
+    // signal that we ready to render and ipc
+    app_ready();
+
+    // from here, any data that pass in render function must be guarded
+    // by calling acquire_state and release_state
+
+    AppExampleEvent event;
+    while(1) {
+        if(get_event(&event, 1000)) {
+            if(event.type == AppExampleEvent::EventTypeKey) {
+                // press events
+                if(event.value.input.type == InputTypeShort &&
+                   event.value.input.key == InputKeyBack) {
+                    printf("bye!\n");
+                    return exit();
+                }
+
+                if(event.value.input.type == InputTypeShort &&
+                   event.value.input.key == InputKeyUp) {
+                    // to read or write state you need to execute
+                    // acquire modify release state
+                    acquire_state();
+                    state.example_data = 24;
+                    release_state();
+                }
+            }
+        }
+
+        // signal to force gui update
+        update_gui();
+    };
+}
+
+// render app
+void AppExample::render(Canvas* canvas) {
+    // here you dont need to call acquire_state or release_state
+    // to read or write app state, that already handled by caller
+    canvas_set_color(canvas, ColorBlack);
+    canvas_set_font(canvas, FontPrimary);
+    canvas_draw_str(canvas, 2, state.example_data, "Example app");
+}
+
+// app enter function
+extern "C" uint8_t app_cpp_example(void* p) {
+    AppExample* app = new AppExample();
+    return app->run();
+}