Replace Math with FastMath for improved performance.

FastMath is a drop in replacement for the native Java math class with improved performance and fall backs to the native Java math class if necessary.

https://commons.apache.org/proper/commons-math/javadocs/api-3.3/org/apache/commons/math3/util/FastMath.html

This requires further testing and might cause chunk borders due the FastMath giving slightly different results than the native Java math class.

I also added .idea/Terra.iml to the .gitignore

build.gradle.kts

@@ -48,6 +48,7 @@ dependencies {
     compileOnly("com.googlecode.json-simple:json-simple:1.1")
     implementation(name = "parsii-1.2", group = "")
     implementation("io.papermc:paperlib:1.0.5")
+    implementation("org.apache.commons:commons-math3:3.6.1")
 
     // JUnit.
     testImplementation("org.junit.jupiter:junit-jupiter-api:5.7.0")