imported videoInput library

https://github.com/ofTheo/videoInput -> videoInputSrcAndDemos/libs/videoInput
imported readme from videoInput-upstream

removed trailing whitespace
reformatted with astyle
fixing capitalisation of include-files
mingw's amvideo.h lacks a HEADER define

the "Amvideo.h" file shipped with videoInput has
(among other things) this HEADER define, which i have duplicated.

now we can compile with mingw!
use the included videoInput library

rather than a system provided one.
document included videoInput library