Fix animation strategies IN_EXP, OUT_EXP, and IN_OUT_EXP

These would not give the correct value at the extremes because it's an exponential curve, it doesn't actually ever get to the value, but for practical reason having it be 0 at 0 and 1 at 1 is much preferred. 

IN_OUT_EXP is fixed by implementing it in terms of IN_EXP and OUT_EXP.

GitHub: #129

src/main/kotlin/gg/essential/elementa/constraints/animation/AnimationStrategy.kt

@@ -116,20 +116,23 @@ enum class Animations : AnimationStrategy {
     },
     IN_EXP {
         override fun getValue(percentComplete: Float): Float {
-            return 2f.pow(10 * (percentComplete - 1))
+            return if (percentComplete <= 0f) 0f else 2f.pow(10 * (percentComplete - 1))
         }
     },
     OUT_EXP {
         override fun getValue(percentComplete: Float): Float {
-            return -(2f.pow(-10 * percentComplete)) + 1
+            return if (percentComplete >= 1f) 1f else -(2f.pow(-10 * percentComplete)) + 1
         }
     },
     IN_OUT_EXP {
         override fun getValue(percentComplete: Float): Float {
-            var t = percentComplete * 2
-            if (t < 1) return 0.5f * 2f.pow(10 * (t - 1))
-            t--
-            return 0.5f * (-(2f.pow(-10 * t)) + 2)
+            // We don't need the extra checks, as those are now handled by the functions we call
+            // multiply percentComplete by 2 to normalize range before calling getValue
+            // then divide by two to shrink it to 0.0-0.5
+            return if (percentComplete < 0.5) IN_EXP.getValue(percentComplete * 2) / 2
+            // multiply percentComplete by 2 and subtract one to normalize range before calling getValue
+            // then divide by two to shrink it and add 0.5 to move it upwards, as a continuation of the first half
+            else OUT_EXP.getValue((percentComplete * 2) - 1) / 2 + 0.5f
         }
     },
     IN_CIRCULAR {
@@ -201,4 +204,4 @@ enum class Animations : AnimationStrategy {
             return OUT_BOUNCE.getValue(percentComplete * 2 - 1) * 0.5f + 0.5f
         }
     }
-}
+}