Filesystem improvements and more (#148)

- Rename `assets` and `config` partitions to `system` and `data`
- Change partition type from `spiffs` to `fat`, so we can have sub-directories
- Fix crash when doing WiFi scan: Increased system event task size to 3kB. 
- Free up IRAM on ESP32 (it was required for the Core2, but I also freed up the same amount for Yellow Board)
- Introduced `Paths` objects that can be retrieved by `AppContext` and `ServiceContext`. Apps and services now have their own relative paths. Assets were re-arranged into the correct paths.
- Rename simulator window title to "Tactility"
- Refactored statusbar widget so it persists icon paths properly (it kept a const char* reference, but didn't copy it, so it crashed when the related std::string was destroyed)
- Created `Partitions.h` to expose some useful variables
- Moved USB config in various `sdkconfig`  (it was part of the "default" section, but it shouldn't be)
- Updated domain name

TactilityCore/Source/file/File.cpp

@@ -49,7 +49,7 @@ static std::unique_ptr<uint8_t[]> readBinaryInternal(const std::string& filepath
     size_t buffer_offset = 0;
     while (buffer_offset < content_length) {
         size_t bytes_read = fread(&data.get()[buffer_offset], 1, content_length - buffer_offset, file);
-        TT_LOG_I(TAG, "Read %d bytes", bytes_read);
+        TT_LOG_D(TAG, "Read %d bytes", bytes_read);
         if (bytes_read > 0) {
             buffer_offset += bytes_read;
         } else { // Something went wrong?
@@ -71,11 +71,15 @@ std::unique_ptr<uint8_t[]> readBinary(const std::string& filepath, size_t& outSi
 std::unique_ptr<uint8_t[]> readString(const std::string& filepath) {
     size_t size = 0;
     auto data = readBinaryInternal(filepath, size, 1);
-    if (size > 0) {
+    if (data == nullptr) {
+        return nullptr;
+    } else if (size > 0) {
         data.get()[size] = 0; // Append null terminator
         return data;
-    } else {
-        return nullptr;
+    } else { // Empty file: return empty string
+        auto value = std::make_unique<uint8_t[]>(1);
+        value[0] = 0;
+        return value;
     }
 }