If the cmake user variable COPY_DEPENDENCIES is set, this script will
make it so that a windows build will automatically copy all required
dependencies (FFmpeg, x264, and Qt5) to the respective
additional_install_files\exec(32|64) directory.  This makes it much
easier to set up a development environment on windows, and much easier
to make usable test builds.

It will also copy the appropriate Direct3D compiler DLL, along with
dependencies of dependencies (the icu*.dll and EGL/GLES files for Qt)

There were a *lot* of warnings, managed to remove most of them.

Also, put warning flags before C_FLAGS and CXX_FLAGS, rather than after,
as -Wall -Wextra was overwriting flags that came before it.

Also, move cpack related code into its own module, to clean up the main CMakeLists.txt

This requirement is due to rpath usage in the project and SDK location
changes[1] in more recent osx versions

[1] i.e. http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=1fce189e

CMake now works on all platforms

- disable -Wshadow for c++ (less semi-bogus warnings for constructors)
- make gcc use c99 mode