move namespace logic into a separate file. It is useful for users of ABC that need to use symbols without the entire baggage of including abc_global.h

CMake, Makefile: pass the location of arch_flags to the makefile, this way the cmake build does not write to the soruce directory

load_plugin: remove a check that the binary exists when a plugin command runs - the registration was successful, so the binary should exist. The check was remove to allow the -p option for load_plugin to work.

Add a -p option to load_plugin, given this option, the command does not require an absolute path for theplugin. Instead, the shell searches PATH for it.