COC Support

[mikalcallahan]

I noticed that using the vim extension COC, floating windows would become illegible due to poor contrast. COC relies on Pmenu for vim and NormalFloat (if exists) for nvim.

Changing hi Pmenu ctermbg=8 ctermfg=7 to hi Pmenu ctermbg=NONE ctermfg=5

renders the floating window in a legible manner with similar contrast to using wal with vs code.

Tested working on nvim v0.4.4 and vim v8.2.850