Cleanup and improvements (#194)

- Lots of changes for migrating C code to C++
- Improved `Lockable` in several ways like adding `withLock()` (+ tests)
- Improved `Semaphore` a bit for improved readability, and also added some tests
- Upgrade Linux machine in GitHub Actions so that we can compile with a newer GCC
- Simplification of WiFi connection
- Updated funding options
- (and more)

TactilityC/Source/tt_semaphore.cpp

@@ -22,7 +22,7 @@ bool tt_semaphore_release(SemaphoreHandle handle) {
 }
 
 uint32_t tt_semaphore_get_count(SemaphoreHandle handle) {
-    return HANDLE_AS_SEMAPHORE(handle)->getCount();
+    return HANDLE_AS_SEMAPHORE(handle)->getAvailable();
 }
 
 }