Use valid category value in library.properties
Use valid category value in library.properties

Use of a category value other than the list of valid categories found in
the Arduino Library Specification:

https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5:-Library-specification#libraryproperties-file-format
causes a warning on every compilation in Arduino 1.6.6 or newer:
WARNING: Category 'Font' in library Arduboy-TinyFont is not valid.
Setting to 'Uncategorized'

yinkou/Arduboy-TinyFont,yinkou/Arduboy-TinyFont