Now using external CMake Module that should hopefully fix all my compiler setting C++11 problems.
Fixed compile error, make value a dependent type.
Moving stack allocation from task_context into contexts platform abstraction. This should work better for fibers.
Added destroy_context(context*) function, called from task_context d'tor.

Adaptes ucontext code, TODO: Boost.Context and Windows Fibers.
Fixed a major bug in the current use of boost::context::make_fcontext that caused overwritten memory and that was the reason why it never worked properly.
Implemented new context abstraction interface for boost.context.
Reduced memory usage of context, similar to boost context implementation