This makes it easier to set BUILD_TESTS (introduced in
87ea0392) from ccmake/cmake-gui

This warning is somewhat insignificant for most of what we do; just
warns about missing braces for sub-structures, but most of the time it
wrongly triggers on = {0}, which is a standard way of initializing a
structure to 0 in C.

mingw-w64 defaults to xp, so when building we set it to vista because
function CancelIoEx is used in ipc-util/pipe-windows.c.

http://msdn.microsoft.com/en-us/library/windows/desktop/aa363792.aspx

Because libobs-opengl is a public library, it's customary to have SONAME
embedded in the library file.  Also remove the prefix override and
remove the prefixing "lib" from the output name.  This also requires us
to pass the library file name to dlopen invocations.

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