RFR: 8075703 "jdk.javadoc" module exports "com.sun.tools.javadoc" package which contains a lot of internal API.

[Jonathan Gibbons]

Please review this fix to move internal classes from an exported package.

Although the webrev appears long, the work itself is fundamentally simple:

Using an IDE, all classes in com.sun.tools.javadoc except Main were moved
as one into a subpackage com.sun.tools.javadoc.main.  A few constructors
in Start had to be fixed by hand, by changing their access from 
package-private
to public.

No other changes were made.  All tests continue to pass.

JBS: https://bugs.openjdk.java.net/browse/JDK-8075703
Review: http://cr.openjdk.java.net/~jjg/8075703/webrev.00/

-- Jon