Devicetree updates (#481)

* **New Features**
  * Added I2S audio support (i2s0) for LilyGO TLora Pager, M5Stack Cardputer (standard & Adv), M5Stack Core2, M5Stack CoreS3, and Guition JC1060P; moved i2s0 entry in LilyGO TDeck.

* **Chores**
  * Device-tree grammar now separately recognizes and ignores line (//) and block (/* */) comments.
  * Added reference docs to severa DTS files

* **Documentation**
  * Reworked ideas/roadmap

Documentation/ideas.md

@@ -3,18 +3,29 @@
 ## Before release
 
 - Add `// SPDX-License-Identifier: GPL-3.0-only` and `// SPDX-License-Identifier: Apache-2.0` to individual files in the project
-- Change ButtonControl to work with interrupts and xQueue
-- TCA9534 keyboards should use interrupts
-- GT911 drivers should use interrupts if it's stable
 - Elecrow Basic & Advance 3.5" memory issue: not enough memory for App Hub
 - App Hub crashes if you close it while an app is being installed
-- Fix glitches when installing app via App Hub with 4.3" Waveshare
 - Calculator bugs (see GitHub issue)
 - Try out speed optimizations: https://docs.espressif.com/projects/esp-faq/en/latest/software-framework/peripherals/lcd.html
   (relates to CONFIG_ESP32S3_DATA_CACHE_LINE_64B that is in use for RGB displays via the `device.properties` fix/workaround)
 
 ## Higher Priority
 
+- Add kernel listening mechanism so that the root device init can be notified when a device becomes available: 
+  Callback for device/start stop with filtering on device type:
+    - on_before_start: e.g. to do the CS pin hack for SD card on a shared bus
+    - on_after_start: e.g. to initialize an I2S device via its I2C connection, once I2C becomes available
+    - on_before_stop: e.g. to stop using a device that was started before
+    - on_after_stop: ?
+- DTS: support for #defines
+- DTS: support for aliases
+- SPI kernel driver
+- iomux kernel driver
+- Kernel concepts for ELF loading (generic approach for GUI apps, console apps, libraries).
+- Fix glitches when installing app via App Hub with 4.3" Waveshare
+- TCA9534 keyboards should use interrupts
+- GT911 drivers should use interrupts if it's stable
+- Change ButtonControl to work with interrupts and xQueue
 - Fix Cardputer (original): use LV_KEY_NEXT and _PREV in keyboard mapping instead of encoder driver hack (and check GPIO app if it then hangs too)
 - Logging with a function that uses std::format
 - Expose http::download() and main dispatcher to TactiltyC.
@@ -35,6 +46,8 @@
 
 ## Medium Priority
 
+- Filtering for apps in App Hub:
+  - apps that only work on a specific device
 - Diceware app has large "+" and "-' buttons on Cardputer. It should be smaller.
 - Create PwmRgbLedDevice class and implement it for all CYD devices
 - TactilityTool: Make API compatibility table (and check for compatibility in the tool itself)
@@ -77,6 +90,8 @@
 - `UiScale` implementation for devices like the CYD 2432S032C
 - Bug: CYD 2432S032C screen rotation fails due to touch driver issue
 - Calculator app should show regular text input field on non-touch devices that have a keyboard (Cardputer, T-Lora Pager)
+- Allow for WSAD keys to navigate LVGL (this is extra nice for cardputer, but just handy in general)
+- Create a "How to" app for a device. It could explain things like keyboard navigation on first start.
 
 # Nice-to-haves
 
@@ -115,29 +130,8 @@
 - Display touch calibration
 - RSS reader
 - Static file web server (with option to specify path and port)
-- Diceware
 - Port TamaFi https://github.com/cifertech/TamaFi
 
-# App Store
-
-- Register user
-    - Name
-    - Company
-    - Email
-    - Password
-- Create/destroy session
-- List apps
-    - Install app
-    - App ID
-    - App version
-- Add/remove API key
-- Upload app
-    - Category
-    - File
-    - Name
-    - Description
-- List apps
-
 # Notes on firmware size
 
 - adding esp_http_client (with esp_event) added about 100kB