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

applications/bt/bt_settings_app/bt_settings_app.h

@@ -6,7 +6,7 @@
 #include <gui/view_dispatcher.h>
 #include <gui/scene_manager.h>
 
-#include <gui/modules/variable-item-list.h>
+#include <gui/modules/variable_item_list.h>
 
 #include "../bt_settings.h"
 #include "scenes/bt_settings_scene.h"

applications/bt/bt_settings_app/scenes/bt_settings_scene_start.c

@@ -1,5 +1,5 @@
 #include "../bt_settings_app.h"
-#include "furi-hal-bt.h"
+#include "furi_hal_bt.h"
 
 enum BtSetting {
     BtSettingOff,