Clear column width cache after updating grid style

Fixes arch1t3cht#11

Author: arch1t3cht

src/base_grid.cpp

@@ -186,6 +186,9 @@ void BaseGrid::UpdateStyle() {
 	row_colors.SelectedComment.SetColour(to_wx(OPT_GET("Colour/Subtitle Grid/Background/Selected Comment")->GetColor()));
 	row_colors.LeftCol.SetColour(to_wx(OPT_GET("Colour/Subtitle Grid/Left Column")->GetColor()));
 
+	if (width_helper)
+		width_helper->ClearCache();
+
 	SetColumnWidths();
 
 	AdjustScrollbar();

src/grid_column.h

@@ -41,6 +41,7 @@ class WidthHelper {
 public:
 	void SetDC(wxDC *dc) { this->dc = dc; }
 	void Age();
+	void ClearCache() { widths.clear(); };
 
 	int operator()(boost::flyweight<std::string> const& str);
 	int operator()(std::string const& str);