Gephi runs out of memory without warning the user

[Mathieu Bastian]

The Java JVM has a maximum memory setting (Xmx) fixed at startup. The default maximum memory with Gephi is 512m.

Running out of memory is the most common reason of Gephi freezing or crashing. The user is unaware of the memory limit and often doesn't know it can be increased (up to a maximum value depending of the physical memory).

We need a system to warn the user about the memory starvation and be able to automatically increase the limit.

[Mathieu Bastian (mathieu.bastian)]

Implemented in rev 2260