title: VS Code giving header errors for Arduino? Missing official header?
body: <p>I've recently started developing for Arduino. Initially I used the Arduino IDE but I soon realised it was not up to par. Development was considerably slower with the need for IDE restarts every now and then. I found VS Code with the Arduino Extension which I've come to love. However I have a few issues and I'm not sure how to solve it.</p>
  
  <p>First of all vs code throws #include errors and asks me to update IntelliSense. However it builds/uploads and runs perfectly well, it also finds the classes etc. defined in said includes so it looks like it's a false positive in some way (i.e. the path is included in includePath settings). Reading the error message also shows it having issues finding a header referenced in Arduino.h called "avr/pgmspace.h". I'm unsure if these errors are related. pgmspace.h is nowhere to be found (it should have been included in the Arduino SDK).</p>
  
  <p>Finally because of the #include error anything related to that particular header file will not be highlighted properly and is just plain gray text which is a bit annoying.</p>
  
  <p>Anyone knows how to fix this? I'm on a Mac btw.</p>
  
  <p><a href="https://i.stack.imgur.com/Rfnnp.png" rel="noreferrer"><img src="https://i.stack.imgur.com/Rfnnp.png" alt="Error messages"></a></p>