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)

Tests/TactilityCore/SemaphoreTest.cpp

@@ -0,0 +1,35 @@
+#include "doctest.h"
+#include "Semaphore.h"
+
+using namespace tt;
+
+// We want a distinct test for 1 item, because it creates the Semaphore differently
+TEST_CASE("a Semaphore with max count of 1 can be acquired exactly once") {
+    auto semaphore = Semaphore(1);
+    CHECK_EQ(semaphore.acquire(0), true);
+    CHECK_EQ(semaphore.getAvailable(), 0);
+    CHECK_EQ(semaphore.acquire(0), false);
+    CHECK_EQ(semaphore.release(), true);
+    CHECK_EQ(semaphore.getAvailable(), 1);
+}
+
+TEST_CASE("a Semaphore with max count of 2 can be acquired exactly twice") {
+    auto semaphore = Semaphore(2);
+    CHECK_EQ(semaphore.acquire(0), true);
+    CHECK_EQ(semaphore.getAvailable(), 1);
+    CHECK_EQ(semaphore.acquire(0), true);
+    CHECK_EQ(semaphore.getAvailable(), 0);
+    CHECK_EQ(semaphore.acquire(0), false);
+    CHECK_EQ(semaphore.release(), true);
+    CHECK_EQ(semaphore.getAvailable(), 1);
+    CHECK_EQ(semaphore.release(), true);
+    CHECK_EQ(semaphore.getAvailable(), 2);
+}
+
+TEST_CASE("the semaphore count should be correct initially") {
+    auto semaphore_a = Semaphore(2);
+    CHECK_EQ(semaphore_a.getAvailable(), 2);
+
+    auto semaphore_b = Semaphore(2, 0);
+    CHECK_EQ(semaphore_b.getAvailable(), 0);
+}