Move the JavaFX files written in Kotlin to the FX module.

fx/build.gradle

@@ -1,3 +1,6 @@
+plugins {
+  id 'org.jetbrains.kotlin.jvm' version '1.1.3'
+}
 apply plugin: 'application'
 
 dependencies {

fx/src/main/kotlin/org/nwapw/abacus/fx/HistoryModel.kt

@@ -0,0 +1,32 @@
+package org.nwapw.abacus.fx
+
+import javafx.beans.property.SimpleStringProperty
+
+/**
+ * A model representing an input / output in the calculator.
+ *
+ * The HistoryModel class stores a record of a single user-provided input,
+ * its parsed form as it was interpreted by the calculator, and the output
+ * that was provided by the calculator. These are represented as properties
+ * to allow easy access by JavaFX cells.
+ *
+ * @param input the user input
+ * @param parsed the parsed version of the input.
+ * @param output the output string.
+ */
+class HistoryModel(input: String, parsed: String, output: String){
+
+    /**
+     * The property that holds the input.
+     */
+    val inputProperty = SimpleStringProperty(input)
+    /**
+     * The property that holds the parsed input.
+     */
+    val parsedProperty = SimpleStringProperty(parsed)
+    /**
+     * The property that holds the output.
+     */
+    val outputProperty = SimpleStringProperty(output)
+
+}

fx/src/main/kotlin/org/nwapw/abacus/fx/ToggleablePlugin.kt

@@ -0,0 +1,31 @@
+package org.nwapw.abacus.fx
+
+import javafx.beans.property.SimpleBooleanProperty
+
+/**
+ * A model representing a plugin that can be disabled or enabled.
+ *
+ * ToggleablePlugin is a model that is used to present to the user the option
+ * of disabling / enabling plugins. The class name in this plugin is stored if
+ * its "enabledPropery" is false, essentially blacklisting the plugin.
+ *
+ * @param className the name of the class that this model concerns.
+ * @param enabled whether or not the model should start enabled.
+ */
+class ToggleablePlugin (val className: String, enabled: Boolean) {
+
+    /**
+     * The property used to interact with JavaFX components.
+     */
+    val enabledProperty = SimpleBooleanProperty(enabled)
+
+    /**
+     * Checks whether this plugin is currently enabled or not.
+     *
+     * @return true if it is enabled, false otherwise.
+     */
+    fun isEnabled(): Boolean {
+        return enabledProperty.value
+    }
+
+}