Revert "remove non-existent function calls"

This reverts commit 9b4159c.

Author: nmwsharp

src/render/opengl/gl_engine_glfw.cpp

@@ -169,8 +169,14 @@ void GLEngineGLFW::configureImGui() {
     ImGuiIO& io = ImGui::GetIO();
     io.Fonts->Clear();
 
+    // these are necessary if different fonts are loaded in the callback
+    // (don't totally understand why, allegedly it may change in the future)
+    ImGui_ImplOpenGL3_DestroyFontsTexture();
+
     ImFontAtlas* _unused;
     std::tie(_unused, regularFont, monoFont) = options::prepareImGuiFontsCallback();
+
+    ImGui_ImplOpenGL3_CreateFontsTexture();
   }