Implement UI scaling and more (#501)

**New Features**
 * Runtime font accessors and new symbol fonts for text, launcher, statusbar, and shared icons.
 * Added font height base setting to device.properties
 * Text fonts now have 3 sizes: small, default, large

**Improvements**
 * Renamed `UiScale` to `UiDensity`
 * Statusbar, toolbar and many UI components now compute heights and spacing from fonts/density.
 * SSD1306 initialization sequence refined for more stable startup.
 * Multiple image assets replaced by symbol-font rendering.
 * Many layout improvements related to density, font scaling and icon scaling
 * Updated folder name capitalization for newer style

TactilityKernel/include/tactility/delay.h

@@ -0,0 +1,54 @@
+#pragma once
+
+#include "time.h"
+#include <stdint.h>
+
+#ifdef ESP_PLATFORM
+#include <rom/ets_sys.h>
+#else
+#include <unistd.h>
+#endif
+
+#include <tactility/freertos/freertos.h>
+#include <tactility/check.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Delay the current task for the specified amount of ticks
+ * @warning Does not work in ISR context
+ */
+static inline void delay_ticks(TickType_t ticks) {
+    check(xPortInIsrContext() == pdFALSE);
+    if (ticks == 0U) {
+        taskYIELD();
+    } else {
+        vTaskDelay(ticks);
+    }
+}
+
+/**
+ * Delay the current task for the specified amount of milliseconds
+ * @warning Does not work in ISR context
+ */
+static inline void delay_millis(uint32_t milliSeconds) {
+    delay_ticks(millis_to_ticks(milliSeconds));
+}
+
+/**
+ * Stall the currently active CPU core for the specified amount of microseconds.
+ * This does not allow other tasks to run on the stalled CPU core.
+ */
+static inline void delay_micros(uint32_t microseconds) {
+#ifdef ESP_PLATFORM
+    ets_delay_us(microseconds);
+#else
+    usleep(microseconds);
+#endif
+}
+
+#ifdef __cplusplus
+}
+#endif