Fix :GoSameIds for light background, GUI, and after changing colour schemes (#983)
Fix :GoSameIds for light background, GUI, and after changing colour schemes (#983)

* Fix :GoSameIds for light background and after changing colour schemes

This does two things:

- For light backgrounds the "highlighted" text is typically the same colour as
  the normal text. So use the `background` setting to set a more appropriate
  colour. I know I can set my own colour, but it would IMHO be better if it just
  works by default.

- The second issue is that most (if not all) colour schemes do this at the
  start:

		" Remove all existing highlighting and set the defaults.
		hi clear

  Which resets all custom highlight groups (except for `:hi link`). So just
  using a "bare" `:hi ctermfg=...` won't work after changing colour schemes:

		:hi goSameId
		goSameId       xxx term=bold cterm=bold ctermfg=0 ctermbg=121

		:colorscheme default

		:hi goSameId
		goSameId       xxx cleared

  The solution is to hook into the `ColorScheme` autocommand.

* Also set GUI

vim-IDE/vim-go,andviro/vim-go,vim-IDE/vim-go,vim-IDE/vim-go,andviro/vim-go