vitalize
s:named_map and s:macro_map should be initialized on emap#load()

s:named_map and s:macro_map should be initialized
every time vimrc is reloaded.
emap#load() is supposed to be called at the top of .vimrc .
update help: emap#load(), emap#define_ex_commands(), emap#init_map_info()
update help: remove unnecessary references