3.1 Changes in update 1

Visual changes:

-"Back to index" button visually changed, added "go to previous page" and "go to next page"-buttons, and added a "Index"-picture.
-Changed scrollbar colours
-Better list of shortcut keys in chapter 1.2
-Replaced some PT2 commands with shortcut keys
-Removed typos
-Divided smashable fences and glass into separate pages

New information:

-Added "smashable objects" and "shrapnel materials" into chapter 1.3
-Updated unit conversion information, and added a tip there
-Other minor additions
-Added "other smashable stuff" under smashable environment specs
-Added "global lighting data"-chapter
-Figured out some opponent path numbers
-Added skidmark material list in "material modifiers"
-Added "races.txt-editing"-chapter
-New vehicle types for drones
-Added "bounding shapes"-chapter