Add cell scaling options

Add a cell_height_scale and cell_width_scale option which is supported
since vte3 0.52.

config

@@ -2,6 +2,8 @@
 #allow_bold = true
 #audible_bell = false
 #bold_is_bright = true
+#cell_height_scale = 1.0
+#cell_width_scale = 1.0
 #clickable_url = true
 #dynamic_title = true
 font = Monospace 9

man/termite.config.5

@@ -41,6 +41,10 @@ The font description for the terminal's font.
 Enables entering fullscreen mode by pressing F11.
 .IP \fIicon_name\fR
 The name of the icon to be used for the terminal process.
+.IP \fIcell_height_scale\fR
+Scale the height of character cells. Valid values range from 1.0 to 2.0.
+.IP \fIcell_width_scale\fR
+Scale the width of character cells. Valid values range from 1.0 to 2.0.
 .IP \fImodify_other_keys\fR
 Emit escape sequences for extra keys, like the \fBmodifyOtherKeys\fR
 resource for \fBxterm\fR(1).

termite.cc

@@ -1481,6 +1481,8 @@ static void set_config(GtkWindow *window, VteTerminal *vte, GtkWidget *scrollbar
 #endif
 #if VTE_CHECK_VERSION (0, 51, 2)
     vte_terminal_set_bold_is_bright(vte, cfg_bool("bold_is_bright", TRUE));
+    vte_terminal_set_cell_height_scale(vte, get_config_double(config, "options", "cell_height_scale").get_value_or(1.0));
+    vte_terminal_set_cell_width_scale(vte, get_config_double(config, "options", "cell_width_scale").get_value_or(1.0));
 #endif
     info->dynamic_title = cfg_bool("dynamic_title", TRUE);
     info->urgent_on_bell = cfg_bool("urgent_on_bell", TRUE);