Thread, Timer and flash.sh improvements (#165)

- Various improvements to Thread and Timer:
  - Remove "mark as static" option as it is unused
  - Implemented core pinning for ESP32 platforms
  - Use `TickType_t` consistently (instead of `uint32_t`)
  - Use `enum class` instead of `enum`
- Fix for `flash.sh` not working when using `pip` to install `esptool`

Tests/TactilityCore/MutexTest.cpp

@@ -23,12 +23,12 @@ TEST_CASE("a mutex can block a thread") {
     thread.start();
 
     kernel::delayMillis(5);
-    CHECK_EQ(thread.getState(), Thread::StateRunning);
+    CHECK_EQ(thread.getState(), Thread::State::Running);
 
     mutex.unlock();
 
     kernel::delayMillis(5);
-    CHECK_EQ(thread.getState(), Thread::StateStopped);
+    CHECK_EQ(thread.getState(), Thread::State::Stopped);
 
     thread.join();
 }