Added empty() function to pool array types

doc/classes/PoolByteArray.xml

@@ -53,6 +53,13 @@
 				Returns a new [PoolByteArray] with the data decompressed. Set [code]buffer_size[/code] to the size of the uncompressed data. Set the compression mode using one of [enum File.CompressionMode]'s constants.
 			</description>
 		</method>
+		<method name="empty">
+			<return type="bool">
+			</return>
+			<description>
+				Returns [code]true[/code] if the array is empty.
+			</description>
+		</method>
 		<method name="get_string_from_ascii">
 			<return type="String">
 			</return>

doc/classes/PoolColorArray.xml

@@ -33,6 +33,13 @@
 				Appends a [PoolColorArray] at the end of this array.
 			</description>
 		</method>
+		<method name="empty">
+			<return type="bool">
+			</return>
+			<description>
+				Returns [code]true[/code] if the array is empty.
+			</description>
+		</method>
 		<method name="insert">
 			<return type="int">
 			</return>

doc/classes/PoolIntArray.xml

@@ -34,6 +34,13 @@
 				Appends a [PoolIntArray] at the end of this array.
 			</description>
 		</method>
+		<method name="empty">
+			<return type="bool">
+			</return>
+			<description>
+				Returns [code]true[/code] if the array is empty.
+			</description>
+		</method>
 		<method name="insert">
 			<return type="int">
 			</return>

doc/classes/PoolRealArray.xml

@@ -33,6 +33,13 @@
 				Appends a [PoolRealArray] at the end of this array.
 			</description>
 		</method>
+		<method name="empty">
+			<return type="bool">
+			</return>
+			<description>
+				Returns [code]true[/code] if the array is empty.
+			</description>
+		</method>
 		<method name="insert">
 			<return type="int">
 			</return>

doc/classes/PoolStringArray.xml

@@ -33,6 +33,13 @@
 				Appends a [PoolStringArray] at the end of this array.
 			</description>
 		</method>
+		<method name="empty">
+			<return type="bool">
+			</return>
+			<description>
+				Returns [code]true[/code] if the array is empty.
+			</description>
+		</method>
 		<method name="insert">
 			<return type="int">
 			</return>

doc/classes/PoolVector2Array.xml

@@ -33,6 +33,13 @@
 				Appends a [PoolVector2Array] at the end of this array.
 			</description>
 		</method>
+		<method name="empty">
+			<return type="bool">
+			</return>
+			<description>
+				Returns [code]true[/code] if the array is empty.
+			</description>
+		</method>
 		<method name="insert">
 			<return type="int">
 			</return>

doc/classes/PoolVector3Array.xml

@@ -33,6 +33,13 @@
 				Appends a [PoolVector3Array] at the end of this array.
 			</description>
 		</method>
+		<method name="empty">
+			<return type="bool">
+			</return>
+			<description>
+				Returns [code]true[/code] if the array is empty.
+			</description>
+		</method>
 		<method name="insert">
 			<return type="int">
 			</return>