Rename tokens to sigils

src/test/java/com/keenwrite/sigils/RSigilOperatorTest.java

		}

		- private Tokens createRTokens() {
		+ private Sigils createRTokens() {
		return createTokens( "x(", ")" );
		}

		- private Tokens createYamlTokens() {
		+ private Sigils createYamlTokens() {
		return createTokens( "{{", "}}" );
		}

		- private Tokens createTokens( final String began, final String ended ) {
		- return new Tokens( createToken( began ), createToken( ended ) );
		+ private Sigils createTokens( final String began, final String ended ) {
		+ return new Sigils( createToken( began ), createToken( ended ) );
		}

src/main/java/com/keenwrite/sigils/SigilOperator.java

		*/
		public abstract class SigilOperator implements UnaryOperator<String> {
		- private final Tokens mTokens;
		+ private final Sigils mSigils;

		- SigilOperator( final Tokens tokens ) {
		- mTokens = tokens;
		+ SigilOperator( final Sigils sigils ) {
		+ mSigils = sigils;
		}



		String getBegan() {
		- return mTokens.getBegan();
		+ return mSigils.getBegan();
		}

		String getEnded() {
		- return mTokens.getEnded();
		+ return mSigils.getEnded();
		}

src/main/java/com/keenwrite/sigils/Sigils.java

		+/* Copyright 2020-2021 White Magic Software, Ltd. -- All rights reserved. */
		+package com.keenwrite.sigils;
		+
		+import javafx.beans.property.StringProperty;
		+
		+import java.util.AbstractMap.SimpleImmutableEntry;
		+
		+/**
		+ * Convenience class for pairing a start and an end sigil together.
		+ */
		+public final class Sigilsg
		+ extends SimpleImmutableEntry<StringProperty, StringProperty> {
		+
		+ /**
		+ * Associates a new key-value pair.
		+ *
		+ * @param began The starting sigil.
		+ * @param ended The ending sigil.
		+ */
		+ public Sigils( final StringProperty began, final StringProperty ended ) {
		+ super( began, ended );
		+ }
		+
		+ /**
		+ * @return The opening sigil token.
		+ */
		+ public String getBegan() {
		+ return getKey().get();
		+ }
		+
		+ /**
		+ * @return The closing sigil token, or the empty string if none set.
		+ */
		+ public String getEnded() {
		+ return getValue().get();
		+ }
		+}

src/main/java/com/keenwrite/sigils/Tokens.java

		-/* Copyright 2020-2021 White Magic Software, Ltd. -- All rights reserved. */
		-package com.keenwrite.sigils;
		-
		-import javafx.beans.property.StringProperty;
		-
		-import java.util.AbstractMap.SimpleImmutableEntry;
		-
		-/**
		- * Convenience class for pairing a start and an end sigil together.
		- */
		-public final class Tokens
		- extends SimpleImmutableEntry<StringProperty, StringProperty> {
		-
		- /**
		- * Associates a new key-value pair.
		- *
		- * @param began The starting sigil.
		- * @param ended The ending sigil.
		- */
		- public Tokens( final StringProperty began, final StringProperty ended ) {
		- super( began, ended );
		- }
		-
		- /**
		- * @return The opening sigil token.
		- */
		- public String getBegan() {
		- return getKey().get();
		- }
		-
		- /**
		- * @return The closing sigil token, or the empty string if none set.
		- */
		- public String getEnded() {
		- return getValue().get();
		- }
		-}

src/main/java/com/keenwrite/sigils/YamlSigilOperator.java

		public static final char KEY_SEPARATOR_DEF = '.';

		- public YamlSigilOperator( final Tokens tokens ) {
		- super( tokens );
		+ public YamlSigilOperator( final Sigils sigils ) {
		+ super( sigils );
		}