8035473: [javadoc] Revamp the existing Doclet APIs

[Kumar Srinivasan]

Hi All,

Please review the following build changes:

JDK changes:
* simple entry point change
http://cr.openjdk.java.net/~ksrini/8035473/webrev.07/webrev.jdk.0/

Top forest repo:
* configuration changes to use the new javadoc/doclet implementation
* module dependency changes (*Mandy, Alan*)
http://cr.openjdk.java.net/~ksrini/8035473/webrev.07/webrev.jdk9.0/

Langtools changes:
* please review the build portions, ie.
      make/CompileInterim.gmk
      make/gensrc/Gensrc-jdk.javadoc.gmk
      make/netbeans/langtools/build.xml
* core javadoc changes are reviewed by Jan, Jon, Bhavesh, Oleg, Vicente
http://cr.openjdk.java.net/~ksrini/8035473/webrev.07/webrev.langtools.0/

Thanks
Kumar