Create base class for DSL exceptions

core/src/main/java/it/cavallium/warppi/math/rules/dsl/DslException.java

@@ -0,0 +1,16 @@
+package it.cavallium.warppi.math.rules.dsl;
+
+/**
+ * The superclass of all exceptions which represent errors in DSL code.
+ */
+public abstract class DslException extends Exception {
+	/**
+	 * @return The index at which the error starts in the source string.
+	 */
+	public abstract int getPosition();
+
+	/**
+	 * @return The length of the error in the source string.
+	 */
+	public abstract int getLength();
+}