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/LockableTest.cpp

@@ -0,0 +1,39 @@
+#include "Lockable.h"
+#include "Semaphore.h"
+#include "doctest.h"
+#include <Mutex.h>
+
+using namespace tt;
+
+TEST_CASE("withLock() locks correctly on Semaphore") {
+    auto semaphore = std::make_shared<Semaphore>(2U);
+    semaphore->withLock([semaphore](){
+        CHECK_EQ(semaphore->getAvailable(), 1);
+    });
+}
+
+TEST_CASE("withLock() unlocks correctly on Semaphore") {
+    auto semaphore = std::make_shared<Semaphore>(2U);
+    semaphore->withLock([=](){
+        // NO-OP
+    });
+
+    CHECK_EQ(semaphore->getAvailable(), 2);
+}
+
+TEST_CASE("withLock() locks correctly on Mutex") {
+    auto mutex = std::make_shared<Mutex>();
+    mutex->withLock([mutex](){
+        CHECK_EQ(mutex->lock(1), false);
+    });
+}
+
+TEST_CASE("withLock() unlocks correctly on Mutex") {
+    auto mutex = std::make_shared<Mutex>();
+    mutex->withLock([=](){
+      // NO-OP
+    });
+
+    CHECK_EQ(mutex->lock(1), true);
+    CHECK_EQ(mutex->unlock(), true);
+}