Added a comment to metaprogramming template, as a replacement has been introduced in the new C++11 standard.
Merge branch 'develop' into feature/TCS3414-driver
Added documentation. Modified comments only.
 * Added new class in xpcc::color: Rgba for colors in Red, Green, Blue + Alpha. This class uses a template to choose the underlying type. Thus it it more flexible than xpcc::color::Rgb. Also it has functions to calculate the color values relative to the overall luminance with parametrizable calculation base type. It overloads the operator<<.
 * Cleaned up TCS3414 color sensor example.
 * TCS3414 driver: Reduced redundancy in comments
 * TCS3414 driver: Introduced common return type so that it is not neccessary to comment each return value but the type has a fixed meaning.
 * TCS3414 driver: Now xpcc::color::Rgba is used