Added io submodule

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "io"]
+	path = io
+	url = git@git.blackmark.me:avr/io.git

README.md

@@ -45,8 +45,8 @@ The PWM mode of the hardware timer can also be used. Additionally, if PWM is nee
 ## Goals
 
 - IO
-    - [ ] Interface for io-pins
-    - [ ] Interface for io-ports
+    - [x] Interface for io-pins
+    - [x] Interface for io-ports
     - [ ] Interface for mapping io-pins onto virtual io-ports, where the pins do not have to be located on the same hardware port
 - ADC
     - [ ] Support all hardware provided configuration options