Jalview-JS/JAL-3253-applet JAL-3192 secondary core files

Jalview-JS/JAL-3253-applet JAL-3192 secondary core files

buildcore now creates core_stevesoft (350K uncompressed) and core_jvjmol
(2.9M uncompressed)

Still needs some tweaking, but the process is relatively
straightforward:

1) To know what files to include, make sure you are using the core
version of the html file, and, after exercizing the program, issue:

J2S._saveFile('_j2sclasslist.txt',
Clazz.ClassFilesLoaded.sort().join('\n'))

(Sorry, I could make that simpler, I know.)

2) add a section in buildcore.xml that concatenates the desired file set
and turns that into a core file.

3) in the FIRST class loaded for this option, add something like this
static block:
  static
  {
    /**
     * This is the entry class. Load the core file directly, if it
exists. See
     * buildcore.xml.
     *
     *
     * @j2sNative
     *
     *            swingjs.JSUtil.loadStaticResource$S("core/core_stevesoft.z.js");
     */
  }

3) run buildcore.xml

2)