Dropped GCC 4.6 support.

It will now live in compatibility branch only.
Containers: removed superfluous template parameter from EnumSet.

Now that the minimal supported version of GCC is 4.7 it can be replaced
with std::underlying_type.
Add todo to use -std=c++11 instead of -std=c++0x.

Kept for compatibility with compatibility branch.
Merge branch 'master' into compatibility

These three commits in master drop GCC 4.6 support, which we want to
preserve in compatibility branch.
package: deleted MinGW32 PKGBUILD.

Replaced with MinGW-w64 in ArchLinux.
Properly credit all contributors.
doc: fix Interconnect example documentation.
package: added MinGW-w64 Jenkins CI configuration.

Also added missing NaCl configuration to documentation.
Added CORRADE_IS_DEBUG_BUILD preprocessor variable.

Defined by CMake on multi-configuration build systems if given build
configuration is Debug. Not defined in any case on single-configuration
build sytems.
Be consistent and use our own platform definitions.
Added CORRADE_TARGET_APPLE CMake and preprocessor variable.

To replace CMake's APPLE and preprocessor __APPLE__ with some
consistency.
Merge branch 'master' into compatibility