Level Tweaks

 - Modified signs and dialog boxes to no longer stop the game. They close once you've gotten far enough from them.
 - Modified extra checkpoint in level 2 to be for all difficulties and not just the hardest.
 - Added more explosives to "Explosive Path" level.
 - Added slightly different path to "Dark Descent" level.
 - Modified "Spike Hike" to be level 2.
 - Fixed "Speedy Send-Off" level secret being partially inaccessible.
 - Added new secret area in "Collapsing Citadel" level to replace awkward, and dangerous secret area.
 - Fixed secret front wall of "Into the Pit."