Add textureWidthMax to build.xml. [0]

This adds the textureWidthMax system property to both jar.runlarge and
debug.runlarge, but both lines have been commented out.
[0] Dreamweaver updates synced from web server.
Add "archived_logs" directory to default logback. [1689]
Add JVM flag field to startup prefs. [1534]

This is still a work in progress!

This adds the “JVM_OPTIONS” setting to runMcV.prefs, which allows the
user to supply arbitrary things to the JVM…though I’m leaving this
ability out of the startup scripts for now. One thing we’re going to
need to handle/document is which flags the user should not use (things
like -Xmx=1337m).

Also did some cleanup and javadocs.