This fixes tons of warnings with clang from a recent xcode version on
macOS (and possibly other systems) complaining that an instantiation
of _singleton is required but no definition is available.
Silences the clang warning:
static data member specialization of '_singleton' must
originally be declared in namespace 'Common'; accepted as a C++0x
extension [-Wc++0x-extensions]
Wrapping "namespace Common {}" around the macro assignment causes clang
to complain about a spurious semicolon, and removing the semicolon at
the end of the macro causes some editors to misbehave.
Changing the requirement of using the macro in one namespace (the
global) to another (Common) seems a small price to pay to
silence a warning.
This merge was extremely difficult to carry out. It wasn't entirely SVN's fault -- there were several merges to the branch that were done by hand. Please check for any issues and regressions. Also note that the DS makefile was not copied over since the "one at a time" plugin mode currently has too much fragmentation ie. it doesn't work.
svn-id: r54051
