Fix FindIconv naming consistency
Fix FindFreetype naming and find logic

Freetype is quite complicated, copied most of the logic from the
original FindFreetype module.
Include FindPackageHandleStandardArgs.cmake in every find module using it

It just worked so far because FindCXX11 happend to include it
already, and it also happend to be the first FindModule used.
Fix HINTS/PATHS in Findv4l2 module
Merge pull request #254 from BtbN/cmake-fix

CMake fixes for iconv and Freetype finding