Fix bug with tab rendering

Closes #494.
Resolves #529.
Resolves #512.
Resolves #493.

src/term/mod.rs

@@ -1237,8 +1237,6 @@ impl ansi::Handler for Term {
                     break;
                 }
 
-                self.insert_blank(Column(1));
-
                 col += 1;
 
                 if self.tabs[*col as usize] {

tests/ref.rs

@@ -30,7 +30,6 @@ ref_tests! {
     fish_cc
     indexed_256_colors
     ll
-    tab_bg_highlight
     tab_rendering
     tmux_git_log
     tmux_htop

tests/ref/tab_bg_highlight/alacritty.recording

@@ -1,5 +0,0 @@
-%                                                                               
 
]2;jwilm@jwilm-desk: ~/code/alacritty]1;..ode/alacritty
jwilm@jwilm-desk ➜  ~/code/alacritty  [?1h=[?2004hecho -e "\x1b[48;5;31m1\t2\n\n3\x1b[0;m"echo -e "\x1b[48;5;31m1\t2\n\n3\x1b[0;m"[?1l>[?2004l
-]2;echo -e "\x1b[48;5;31m1\t2\n\n3\x1b[0;m"]1;echo1	2
-
-3
-%                                                                               
 
]2;jwilm@jwilm-desk: ~/code/alacritty]1;..ode/alacritty
jwilm@jwilm-desk ➜  ~/code/alacritty  [?1h=[?2004h

tests/ref/tab_bg_highlight/size.json

@@ -1 +0,0 @@
-{"width":644.0,"height":412.0,"cell_width":8.0,"cell_height":17.0}