added space before format macros for c++11 compat

without a space after " compilation with -std=c++11 fails, because it
assumes the macro to be a string suffix, which it does not know / which is
invalid, because it doesn't start with a underscore
explicit boost:: namespace for c++11 compat

c++11 introduced a std::shared_ptr. With using namespace std and boost the
declaration without explicit namespace is invalid
shared_ptr comparisions to nullptr for c++11

c++11 supports explicit operator bool, which is used by newer boost if
c++11 is enabled, breaking the implicit conversions. A comparision to NULL
is used instead
[appmessenger] make ThreadMessage's parameters signed integers
Merge pull request #4024 from lorem-ipsum/c++11

Minor changes to enable c++11 compilation