Implement new Main wrapper class for utility.jar, to
work around izpack ticket #162http://jira.codehaus.org/browse/IZPACK-162
which prevents us from specifying a main class as it fails on
Windows installations when a full path including a drive letter is specified
(ticket #912)
- move deprecated installer-only classes (Exec, Delete, and Copy) from
i2p.jar into installer/
- replace installer/resources/fixpaths.cmd with an improved method in java
- combine the installer-only utility classes into a single jar and call the
classes from within izpack