keep <plug> mapping not remove

[milanglacier]

Personally I will map multiple keymaps to one execution,
for example I will map <Leader>ss, <Leader>sl to same execution: iron send line,
so deprecating <plug> mapping will make my config be less clearer,
I next need to call mappings = {send_a_line = '<Leader>ss'} first, and then calling nmap <Leader>ss <Leader>sl,
i.e a recursive map, which is not ideal.
For a <plug> style mapping, I can map <leader>ss and <Leader>sl to <Plug>iron-send-a-line which is definetely more clear

[stephenprater]

I agree with this - I hate figuring out a different way to do keymaps for every plugin. Please continue to provide <plug> mappings so we can use Vimscript mappings.