add ! as allowed char to account for `enable_if` macroses encountered on osx
add ! as allowed char to account for `enable_if` macroses encountered on osx

niosus/EasyClangComplete,kgizdov/EasyClangComplete,niosus/EasyClangComplete,kgizdov/EasyClangComplete,niosus/EasyClangComplete,kgizdov/EasyClangComplete,kgizdov/EasyClangComplete