Changed rencache to store font tab_width with font command

Fixes bug where text would be drawn/cached wrongly if more than one tab_width
was used in a given frame

src/rencache.c

···
   RenRect rect;
   RenColor color;
   RenFont *font;
+  int tab_width;
   char text[0];
 } Command;
 
···
       cmd->color = color;
       cmd->font = font;
       cmd->rect = rect;
+      cmd->tab_width = ren_get_font_tab_width(font);
     }
   }
 
···
           ren_draw_rect(cmd->rect, cmd->color);
           break;
         case DRAW_TEXT:
+          ren_set_font_tab_width(cmd->font, cmd->tab_width);
           ren_draw_text(cmd->font, cmd->text, cmd->rect.x, cmd->rect.y, cmd->color);
           break;
       }

src/renderer.c

···
 }
 
 
+int ren_get_font_tab_width(RenFont *font) {
+  GlyphSet *set = get_glyphset(font, '\t');
+  return set->glyphs['\t'].xadvance;
+}
+
+
 int ren_get_font_width(RenFont *font, const char *text) {
   int x = 0;
   const char *p = text;

src/renderer.h

···
 RenFont* ren_load_font(const char *filename, float size);
 void ren_free_font(RenFont *font);
 void ren_set_font_tab_width(RenFont *font, int n);
+int ren_get_font_tab_width(RenFont *font);
 int ren_get_font_width(RenFont *font, const char *text);
 int ren_get_font_height(RenFont *font);