Add U8glib as a dependency to platformio.ini for those who use PlatformIO; this makes compiling even easier as u8glib will be downloaded and included automatically.

Also added the new .pio-related directory to .gitignore, and a few ignores for those who use cmake.

.gitignore

@@ -1,6 +1,6 @@
 #
 # Marlin 3D Printer Firmware
-# Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+# Copyright (C) 2017 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
 #
 # Based on Sprinter and grbl.
 # Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
@@ -118,6 +118,7 @@ tags
 #PlatformIO files/dirs
 .pioenvs
 .piolib
+.piolibdeps
 
 #Visual Studio
 *.sln
@@ -127,3 +128,7 @@ Marlin/Release/
 Marlin/Debug/
 Marlin/__vm/
 Marlin/.vs/
+
+#cmake
+CMakeLists.txt
+Marlin/CMakeLists.txt