#62 Support Xmx parameter to increase heap

[Phil Borlin]

When launching a jar it is not normally possible to set the -Xmx property since you can't change the amount of memory once the vm is started. This patch adds a manifest entry that lets you define the max amount of memory. The strategy used is to reconstruct the path and relaunch the jar under the original conditions in a new vm with the addition of an -Xmx property. Since the launch configurations are gleaned through API only found in Java 1.5, reflection is used. The -Xmx property works under 1.5 and is ignored if the jar is run on a 1.4 jvm.

[Phil Borlin]

[P. Simon Tuffs]

Thanks for this very useful contribution, I will roll it into the next build of 0.98 when I pick it up again (hopefully soon).