Fix the fill_color() method with internal_color usage (using direct drawing primitive)
Use SDL_RenderFillRect instead of SDL_RenderClear to draw a rectangle
We can't use opacity with direct drawing, use alpha channel instead
Setting a transparent background when building a surface is useless
Forgot this rebuild
Revert "Revert 'Don't destroy the software surface when the texture gets created.'"

This reverts commit 03e3fa46bf92823754300d3f4cfc3843382a2436.
Fix comments
Only render a subsurface if its destination rectangle has intersection with parent rectangle
Finally, setting a transparent background when building a surface is useful with software surface
Fix the black background when taking stairs (don't solve the clipping issue)
Fix stairs
Remove tabs.
Fix display position of some hardware subsurface. It properly fix stairs too
Don't care about the destination size at drawing level, use the source one
Fix life and money exceeding the max when the max changes (fix #355).
Merge branch 'master' into texture
Add Debug::check_assertion() overload that takes const char* parameter.

This avoids useless conversions to std::string when the assertion is
true.
Prefer ARGB pixel format.

This is the format of my renderer, so it will avoid conversions. As an
future improvement, it would be better to automatically choose a pixel
format of the renderer.
Revert "Prefer ARGB pixel format."

This reverts commit 6bb1e4c639e347cae1489cac1d500dc6d797e12c.
Coding style.