Project restructuring: add tactility-headless (#55)

- Created `tactility-headless` to support ESP32 firmwares that don't require graphics
- `tactility` subproject now contains both PC and ESP32 code (to avoid having to split up `tactility` and `tactility-headless` into separate projects, which would result in a very complex dependency tree)
- `tactility` subproject is now defined as component for ESP32 and as regular module for PC
- Improvements for dispatcher
- Added `project-structure.puml` to docs
- `Gui` service now depends on `Loader` service instead of the reverse
- Added `statusbar_updater` service for updating Wi-Fi and SD card icons

tactility-headless/CMakeLists.txt

@@ -0,0 +1,48 @@
+cmake_minimum_required(VERSION 3.16)
+
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+if (DEFINED ENV{ESP_IDF_VERSION})
+    file(GLOB_RECURSE SOURCE_FILES src/*.c)
+
+    idf_component_register(
+        SRCS ${SOURCE_FILES}
+        INCLUDE_DIRS "src/"
+        REQUIRES esp_wifi nvs_flash spiffs driver newlib
+    )
+
+    set(ASSETS_SRC_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../data/assets")
+    spiffs_create_partition_image(assets ${ASSETS_SRC_DIR} FLASH_IN_PROJECT)
+
+    set(CONFIG_SRC_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../data/config")
+    spiffs_create_partition_image(config ${CONFIG_SRC_DIR} FLASH_IN_PROJECT)
+
+    target_link_libraries(${COMPONENT_LIB}
+        PUBLIC tactility-core
+    )
+
+    add_definitions(-DESP_PLATFORM)
+else()
+    file(GLOB_RECURSE SOURCES "src/*.c")
+    file(GLOB_RECURSE HEADERS "src/*.h")
+
+    add_library(tactility-headless OBJECT)
+    target_sources(tactility-headless
+        PRIVATE ${SOURCES}
+        PUBLIC ${HEADERS}
+    )
+
+    target_include_directories(tactility-headless
+        PRIVATE src/
+        INTERFACE src/
+    )
+
+    add_definitions(-D_Nullable=)
+    add_definitions(-D_Nonnull=)
+    target_link_libraries(tactility-headless
+        PUBLIC tactility-core
+        PUBLIC freertos_kernel
+    )
+endif()