#168 build-release should not copy files from plugin installation

[Philip Ogren]

the target build-release in ant/sourceforge.xml copies the contents of the currently installed knowtator and copies it into the zip file for release. All of the files should be rebuilt from build.xml/build-plugin results that are written to some other directory. Otherwise, things can get easily confused. For example, I tested the src release zip file by building it after changing the release number. This caused the locally installed knowtator to change and when I ran build-release again it had the wrong version number.