java.lang.OutOfMemoryError & java.lang.StackOverflowError during Maven installation.

[calairoh]

I found some problems in the Maven installation on Windows 10. In particular, in the pgql-spofax project, at a certain point, the build failed due to java.lang.StackOverflowError or java.lang.OutOfMemoryError. Obviously, I set the JAVA_OPTS enviroment variable as described in the readme.md file. Assuming it was a Maven problem, since in my knowledge Maven doesn't read JAVA_OPTS variable, I tried to set the MAVEN_OPTS environment variable with the same values as the JAVA_OPTS variable, and the installation was successful. Maybe, it could be helpful to integrate the MAVEN_OPTS setup in the readme.md file.