release 7.0.0

• reworked some parameters for Maven and ANT plug-ins
• removed maven clear goal
• added embedded Gradle plugin com.igormaznitsa.jcp
• added function STR esc(STR)
• fixed build under JDK 9+
• XML functions work through embedded Apache Xalan and Apache Xerces
• minimal needed Java version changed to 1.8
• refactoring