Improve highlight configurability

- Use separate highlight groups for `texthl` and `linehl` in the
  `current` and `breakpt` `:sign` definitions

- Change default GUI highlighting to be like cterm highlighting

Author: Quinn Strahl

plugin/vdebug.vim

@@ -123,10 +123,12 @@ command! -nargs=? VdebugEval python debugger.handle_eval(<q-args>)
 command! -nargs=+ -complete=customlist,s:OptionNames VdebugOpt python debugger.handle_opt(<f-args>)
 
 " Signs and highlighted lines for breakpoints, etc.
-sign define current text=->  texthl=DbgCurrent linehl=DbgCurrent
-sign define breakpt text=B>  texthl=DbgBreakPt linehl=DbgBreakPt
-hi default DbgCurrent term=reverse ctermfg=White ctermbg=Red gui=reverse
-hi default DbgBreakPt term=reverse ctermfg=White ctermbg=Green gui=reverse
+sign define current text=-> texthl=DbgCurrentSign linehl=DbgCurrentLine
+sign define breakpt text=B> texthl=DbgBreakptSign linehl=DbgBreakptLine
+hi default DbgCurrentLine term=reverse ctermfg=White ctermbg=Red guifg=#ffffff guibg=#ff0000
+hi default DbgCurrentSign term=reverse ctermfg=White ctermbg=Red guifg=#ffffff guibg=#ff0000
+hi default DbgBreakptLine term=reverse ctermfg=White ctermbg=Green guifg=#ffffff guibg=#00ff00
+hi default DbgBreakptSign term=reverse ctermfg=White ctermbg=Green guifg=#ffffff guibg=#00ff00
 
 function! s:OptionNames(A,L,P)
     let arg_to_cursor = strpart(a:L,10,a:P)