rawinput: distinguish between circular and linear analog input (#665)

## Link to GitHub Issue or related Pull Request, if one exists
n/a

## Description of change
Currently, all analogs are treated as circular values that wrap around.
This works for knobs and turntables, but can get weird for linear values
(like tilt sensors and sliders) especially once analog options are
enabled, such as sensitivity.

This PR groups analogs into 3 buckets: circular, linear (centered), and
linear (positive). Linear types get different algorithms applied to it
when options are set (e.g., sensitivity caps out at 0, 1 instead of
wrapping around).

In linear mode:
* Sensitivity value applies an exponential response curve (power curve)
to the original value.
* Multiplier/divisor serves as a linear cut-off.
* Relative mode works as you expect, but of course, values don't wrap
around.
* Invert and deadzone work as you expect (since they applied to the
controller input anyway)
* Smoothing is removed from the UI and has no effect.
* Delay is unaffected.

Also, fix a small bug with -/+ button not working for analog `Delay`
option.

## Testing
WIP

src/spice2x/cfg/analog.cpp

@@ -207,22 +207,38 @@ float Analog::applyMultiplier(float value) {
 }
 
 float Analog::normalizeAnalogValue(float value) {
-    // effectively the same as fmodf(value, 1.f)
-    // for small values, this is MUCH faster than fmodf.
-    float new_value = value;
-    while (new_value > 1.f) {
-        new_value -= 1.f;
+    if (getType() == GameAPI::Analogs::AnalogType::Circular) {
+        // effectively the same as fmodf(value, 1.f)
+        // for small values, this is MUCH faster than fmodf.
+        float new_value = value;
+        while (new_value > 1.f) {
+            new_value -= 1.f;
+        }
+        while (new_value < 0.f) {
+            new_value += 1.f;
+        }
+        return new_value;
+
+    } else {
+        // clamp to [0, 1] range
+        return std::clamp(value, 0.f, 1.f);
     }
-    while (new_value < 0.f) {
-        new_value += 1.f;
-    }
-    return new_value;
 }
 
 float Analog::applyDeadzone(float raw_value) {
     float value = raw_value;
-    const auto deadzone = this->getDeadzone();
-    if (deadzone > 0) {
+    auto deadzone = this->getDeadzone();
+
+    // in the past, positive deadzone applied in the center, negative deadzone applied to 0
+    // after each analog value received a type (circular/linear) this has been simpliifed to
+    // positive values only since we can figure out where the rest value is
+    // for back compat, treat negative value as positive
+    if (deadzone < 0.f) {
+        deadzone = -deadzone;
+    }
+
+    // relative mode assumes that user is using a stick, so center is neutral regardless of analog type
+    if (getType() != GameAPI::Analogs::AnalogType::LinearPositive || isRelativeMode()) {
 
         // calculate values
         const auto delta = value - 0.5f;
@@ -255,7 +271,7 @@ float Analog::applyDeadzone(float raw_value) {
             }
         }
 
-    } else if (deadzone < 0) {
+    } else {
 
         // invert for mirror
         if (this->getDeadzoneMirror()) {
@@ -263,8 +279,8 @@ float Analog::applyDeadzone(float raw_value) {
         }
 
         // deadzone from minimum value
-        if (deadzone > -1 && value > -deadzone) {
-            value = std::min(1.f, (value + deadzone) / (1.f + deadzone));
+        if (deadzone < 1.f && deadzone < value) {
+            value = std::max(0.f, (value - deadzone) / (1.f - deadzone));
         } else {
             value = 0.f;
         }