Replaces Xmx with a percentage-based argument, in this case leaving 5% overhead.
Resolves issue of container OOM/freezing when all memory is allocated to the java application or when users attempt to use unlimited memory of 0. That's because all the allocated memory is set to Xmx by default. Causes Wings resource overhead allocation to be unnecessary.
Expands Forge installer exit code to provide instructions regarding increasing Wings installer resource limits when using unlimited memory (0) as the default 1024MB is not enough to run the installer.
The percentage is set as a floating point, because of a JDK 8 bug with integers
