Refactored text and screenp access so text drawing always refers to the single texts (text_normal and text_big) in video and global myscreen is used directly instead of all the screenp args.
Added rising damage numbers for each walker.  Moving the storage into the screen class might be better so the text doesn't go under other walkers.
Added a little hack to fix premature reference of global myscreen.  This should be fixed for real by making the viewport constructor not use myscreen.
Adjusted rising damage numbers so they are only seen by the people they affect.  Added numbers for cleric heal, but not any other special.
Added colorview tool.
Added walker::hurt_flash for drawing a recolored version when hit.
Added attack_lunge.  Change ATTACK_LUNGE_SIZE to adjust the effect.
Added last_hitpoints display for mini health bar.
Added walker::hit_recoil as a converse to attack_lunge and a complement to hit_flash.
Added hit effect (i.e. a starburst) when a projectile hits.
Added the new feedback effects everywhere that damage is done (I think).
Limited attack lunge and hit recoil to ORDER_LIVING.
Combined settings.yaml and openglad.yaml.  All of the settings are handled by the cfg_store class.  Also added settings for the combat feedback effects.
Added "gore" setting that picks the blood and stain images.  This does not affect any text outside of the level editor.
Added libpng dependency to enable screenshots (press F10 anywhere).
Added libpng flag to Linux build target.
Made an options menu.
Added wrench image for options menu button.
Changed old blood_friendly to the nicer "poof" version.
Merge branch 'combat_feedback' of https://github.com/openglad/openglad into combat_feedback