Improved Pmenu colors

[rodrigore]

Hi, i was trying to replicate the same colors of the Code version when the pop menu for completion appers. Code version looks like this:

The left side show the new version, and the right version show the actual version of palenight.vim

I was planning to do a pull request but I only use the white color of this plugin and I added 3 colors that are not on the variables (some purple variations), so not sure what you think about to add new variable colors or only use the hexadecimal values.

This is the code that I use in order to achieve the left side.

hi Pmenu guibg=#212333
hi PmenuSel guibg=#6A3EB5 guifg=#bfc7d5
hi PmenuSbar guibg=#352B59 guifg=#352B59
hi PmenuThumb guibg=#352B59 guifg=#352B59