Update version number to 1.24

Author: junichi11

manifest.mf

@@ -3,4 +3,4 @@ OpenIDE-Module: org.netbeans.modules.linetools/1
 OpenIDE-Module-Layer: org/netbeans/modules/linetools/resources/layer.xml
 OpenIDE-Module-Localizing-Bundle: org/netbeans/modules/linetools/Bundle.properties
 OpenIDE-Module-Requires: org.netbeans.api.javahelp.Help
-OpenIDE-Module-Specification-Version: 1.23
+OpenIDE-Module-Specification-Version: 1.24