[Tororoi]

Adds a Dead Zone option to the Controls page (input.dead_zone). It defaults to radial.

• Radial (StickCalibration) measures the stick's tilt from the centre. It reads the larger of the two offsets with the game's own curve and gives each axis its share, so diagonals keep their angle. A push straight along an axis reads exactly as Axial does, on both sides of the centre.
• Axial is the game's AxisCalibration. Each stick axis is zeroed on its own, within 49 above and 50 below the centre, and the rest is stretched over 128. Because the smaller axis falls inside its own dead zone, a push within about 23° of an axis reads as exactly on it.

The input layer already stretches a modern stick's circle onto the DualShock 2's square, keeping its direction. The tilt is therefore the larger of the two offsets, which keeps the dead zone round on the physical stick.

The option applies to both sticks on both pads (CGamePad::GetLX…GetRY2). The menus' pointer and the Options screen still call AxisCalibration directly.

Also:

• The label, help and choices in the four shipped translations.
• docs/PC.md: the key in the sample config, and a note under Gamepad sticks.

Tests:

• PlatformConfig.ParsesMouseSettingsAndBindings: the default (radial), a round trip through axial, and a bad value, which keeps the default.
• PlatformPad.RadialDeadZoneMeasuresFromTheCentre:
  • on an axis, either side of the centre, it matches Axial;
  • 15° off an axis it keeps the slant where Axial reads 0;
  • both axes just inside the dead zone read nothing;
  • a diagonal reads each axis as that axis alone would.
• PlatformPad.AxesGoThroughCalibration now sets Axial itself, since it checks the game's per-axis curve.

[SirFancyBacon]

Feels better is an understatement; This is much better than retail