spdlog default pattern defined twice

There are two definitions (and declarations) of the default_pattern for logging, one should do:

• in framework/core/Logging.hpp, line 53, we define corsika::default_pattern
• in detail/framework/core/Logging.inl, line 24, we define corsika::logging::default_pattern

Both definitions use the same pattern. The 2nd definition is used when setting configuring the default logger.

Also, the inline code in one place refers to the variable as logging::default_pattern and in another place using just default_pattern. The namespace qualification is superfluous since the code is in a

namespace logging {
   ...
};

constuct.