Player Movement

Player movement and jumping implemented, uncomplete but most of it's
there.
Player Control Improved, Base Mechanics Complete

Added accel/deccel to player, as well as seperate customiseable values
for a whole host of things that define the feel of the player, including
ground/air drag, max movement speed, gravity coefficient, jump strength,
etc.

These values are loaded in from a config XML file located in
ConfigFiles/PlayerConfig.xml, the designers can fiddle with these values
till there hearts content. If the file isnt found code based defaults
are used, defined in Player.cpp - LoadConfigValues()

Also locked the simulation rate to 60fps with a deltaTime accumulator
based approach, it dosent interpolate between frames, (although this may
have to be implemented later, at least for the player.) Rendering and
simulation are technically uncoupled, but rendering dosent do any
smoothing so it's pointless, at least the game is completely framerate
independent now, for both linear motion and acceleration.
Fixed the damn timestep stutter

The accumulator approach was dumb,(not really, it's pretty smart when
implemented properly but it wasn't in this case.) I took it out because
it was causing a stutter every 60 frames or so(caused by 2 simulation
steps being done at once.) We're back to a more familiar, multiply
deltaTime in based approach. I was confused before by the difference in
implementation between velocity and acceleration, all sorted now.