protonect: added install target and use pkg-config to find dependancis

The install targets for protonect was missing, now the lib and all headers
got installes.

Also make it configurable wether the internal-find algorithm should
be used, or if it is assumed that the depending libraries (libusb/glfw/glew)
are installed in the system. This needs a fix of the include of libusb itself
in the headers.

All changes should be backward compatible.
On 18.11.2014 09:29, Lars wrote:
>
> In examples/protonect/include/libfreenect2/usb/transfer_pool.h:
>
> > @@ -27,7 +27,7 @@
> >  #ifndef TRANSFER_POOL_H_
> >  #define TRANSFER_POOL_H_
> >
> > -#include <libusb.h>
> > +#include <libusb-1.0/libusb.h>
>
> Any reason why you have to include libusb-1.0 - what happend if the 
> library is named otherwise eventually :) ?
>
> My path to libusb.h is "C:\libraries\libusbx\libusb\", so that 
> wouldn't work on my install.
>
In the past the libusb-1.0 was fixed given in the CMakeLists.
The package-config returns the patch to /usr/include and not to 
/usr/include/libusb-1.0/
(which is the corretct way).

For compatibility i could extend the include-path in the CMakeLists 
instead inside the headers, but this is not the way as headers should be 
handeled or installed.


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