terminal: Some improvements to Terminal detection

closes #1730

- Make sure to always call the term extension on TermOpen autocommands
- consistently use the airline_term highlighting group
- hard code the airline_term highlighting group, because by the time the
  function airline#themes#patch() is called the highlighting group
  airline_c would no be defined, so we cannot dynamically get those
  attributes
- In the documentation, mention how the g:airline_mode_map can be set
  including the terminal section

autoload/airline/extensions/term.vim

@@ -7,9 +7,10 @@ function! airline#extensions#term#apply(...)
   if &buftype == 'terminal'
     let spc = g:airline_symbols.space
 
-    call a:1.add_section('airline_a', spc.'TERMINAL'.spc)
+    let name=get(g:airline_mode_map, 't', 't')
+    call a:1.add_section('airline_a', spc.name.spc)
     call a:1.add_section('airline_b', '')
-    call a:1.add_section('airline_c', spc.'%f')
+    call a:1.add_section('airline_term', spc.'%f')
     call a:1.split()
     call a:1.add_section('airline_y', '')
     call a:1.add_section('airline_z', spc.airline#section#create_right(['linenr', 'maxlinenr']))

autoload/airline/themes.vim

@@ -45,8 +45,7 @@ function! airline#themes#patch(palette)
       let a:palette[mode]['airline_error'] = [ '#000000', '#990000', 232, 160 ]
     endif
     if !has_key(a:palette[mode], 'airline_term')
-      "let a:palette[mode]['airline_term'] = [ '#9cffd3', '#202020', 85, 232]
+      let a:palette[mode]['airline_term'] = [ '#9cffd3', '#202020', 85, 232]
-      let a:palette[mode]['airline_term'] = airline#highlighter#get_highlight('airline_c')
     endif
   endfor
 

doc/airline.txt

@@ -184,6 +184,7 @@ values):
       \ 's'  : 'S',
       \ 'S'  : 'S',
       \ '' : 'S',
+      \ 't'  : 'T',
       \ }
 <
 * define the set of filename match queries which excludes a window from having

plugin/airline.vim

@@ -99,6 +99,10 @@ function! s:airline_toggle()
         " Make sure that g_airline_gui_mode is refreshed
         autocmd OptionSet termguicolors call <sid>on_colorscheme_changed()
       endif
+      if exists("##TerminalOpen")
+        " Make sure that g_airline_gui_mode is refreshed
+        autocmd TerminalOpen * call <sid>on_colorscheme_changed()
+      endif
       " Refresh airline for :syntax off
       autocmd SourcePre */syntax/syntax.vim
             \ call airline#extensions#tabline#buffers#invalidate()