Fix #3290

- Mostly remove the duplication between main.cpp's init and irr_driver.cpp's applyResolutionSettings by means of a new function
- Add a new function to ParticleKindManager to preload explosions.
- Increase the length of the function separators in irr_driver.cpp from 80 columns to 96 columns
- Remove a pointless define guard (the entire function was wrapped in the same define guard)
- Add a comment about the effect of the HQ texture setting

Author: Alayan-stk-2

src/graphics/graphical_presets.cpp

@@ -179,6 +179,7 @@ namespace GraphicalPresets
     // --------------------------------------------------------------------------------------------
     int getImageQuality()
     {
+        // If high definition texture is true, the max texture size is 2048. Else, it's 512.
         if (UserConfigParams::m_anisotropic == 4 &&
             (UserConfigParams::m_high_definition_textures & 0x01) == 0x00 &&
             UserConfigParams::m_hq_mipmap == false)