Added TTimo's QuakeLive-style mouse acceleration, thanks Gabriel Schnoering and TTimo for the patch. (#3693)

README

@@ -107,6 +107,9 @@ New cvars
   cl_cURLLib                        - filename of cURL library to load
   cl_consoleKeys                    - space delimited list of key names or
                                       characters that toggle the console
+  cl_mouseAccelStyle                - Set to 1 for QuakeLive mouse acceleration
+                                      behaviour, 0 for standard q3
+  cl_mouseAccelOffset               - Tuning the acceleration curve, see below
 
   s_useOpenAL                       - use the OpenAL sound backend if available
   s_alPrecache                      - cache OpenAL sounds before use
@@ -126,26 +129,28 @@ New cvars
   s_alDriver                        - which OpenAL library to use
   s_alDevice                        - which OpenAL device to use
   s_alAvailableDevices              - list of available OpenAL devices
-
   s_sdlBits                         - SDL bit resolution
   s_sdlSpeed                        - SDL sample rate
   s_sdlChannels                     - SDL number of channels
   s_sdlDevSamps                     - SDL DMA buffer size override
   s_sdlMixSamps                     - SDL mix buffer size override
+  s_backend                         - read only, indicates the current sound
+                                      backend
+  s_muteWhenMinimized               - mute sound when minimized
 
   com_ansiColor                     - enable use of ANSI escape codes in the tty
   com_altivec                       - enable use of altivec on PowerPC systems
   com_standalone                    - Run in standalone mode
   com_maxfpsUnfocused               - Maximum frames per second when unfocused
   com_maxfpsMinimized               - Maximum frames per second when minimized
-  s_backend                         - read only, indicates the current sound
-                                      backend
-  s_muteWhenMinimized               - mute sound when minimized
+
   in_joystickNo                     - select which joystick to use
   in_keyboardDebug                  - print keyboard debug info
-  r_ext_texture_filter_anisotropic  - anisotropic texture filtering
+
   sv_dlURL                          - the base of the HTTP or FTP site that
                                       holds custom pk3 files for your server
+  sv_banFile                        - Name of the file that is used for storing
+                                      the server bans.
 
   net_ip6                           - IPv6 address to bind to
   net_port6                         - port to bind to using the ipv6 address
@@ -160,6 +165,7 @@ New cvars
   net_mcastiface                    - outgoing interface to use for scan
 
   r_allowResize                     - make window resizable (SDL only)
+  r_ext_texture_filter_anisotropic  - anisotropic texture filtering
   r_zProj                           - distance of observer camera to projection
                                       plane in quake3 standard units
   r_greyscale                       - render black and white images
@@ -186,8 +192,6 @@ New cvars
                                       intend to use this.
   r_sdlDriver                       - read only, indicates the SDL driver
                                       backend being used
-  sv_banFile                        - Name of the file that is used for storing
-                                      the server bans.
 
 New commands
   video [filename]        - start video capture (use with demo command)
@@ -225,6 +229,51 @@ Using Demo Data Files
   data, nor is it something that we like to spend much time maintaining or
   supporting.
 
+QuakeLive mouse acceleration (patch and this text written by TTimo from id)
+  I've been using an experimental mouse acceleration code for a while, and
+  decided to make it available to everyone. Don't be too worried if you don't
+  understand the explanations below, this is mostly intended for advanced
+  players:
+  To enable it, set cl_mouseAccelStyle 1 (0 is the default/legacy behavior)
+
+  New style is controlled with 3 cvars:
+
+  sensitivity
+  cl_mouseAccel
+  cl_mouseAccelOffset
+
+  The old code (cl_mouseAccelStyle 0) can be difficult to calibrate because if
+  you have a base sensitivity setup, as soon as you set a non zero acceleration
+  your base sensitivity at low speeds will change as well. The other problem
+  with style 0 is that you are stuck on a square (power of two) acceleration
+  curve.
+
+  The new code tries to solve both problems:
+
+  Once you setup your sensitivity to feel comfortable and accurate enough for
+  low mouse deltas with no acceleration (cl_mouseAccel 0), you can start
+  increasing cl_mouseAccel and tweaking cl_mouseAccelOffset to get the
+  amplification you want for high deltas with little effect on low mouse deltas.
+
+  cl_mouseAccel is a power value. Should be >= 1, 2 will be the same power curve
+  as style 0. The higher the value, the faster the amplification grows with the
+  mouse delta.
+
+  cl_mouseAccelOffset sets how much base mouse delta will be doubled by
+  acceleration. The closer to zero you bring it, the more acceleration will
+  happen at low speeds. This is also very useful if you are changing to a new
+  mouse with higher dpi, if you go from 500 to 1000 dpi, you can divide your
+  cl_mouseAccelOffset by two to keep the same overall 'feel' (you will likely
+  gain in precision when you do that, but that is not related to mouse
+  acceleration).
+
+  Mouse acceleration is tricky to configure, and when you do you'll have to
+  re-learn your aiming. But you will find that it's very much forth it in the
+  long run.
+
+  If you try the new acceleration code and start using it, I'd be very
+  interested by your feedback.
+
 64bit mods
   If you wish to compile external mods as shared libraries on a 64bit platform,
   and the mod source is derived from the id Q3 SDK, you will need to modify the