Update dependencies and candy generator

[kohlschuetter]

• Move plugin and dependency version management to parent POM
• Update plugins and dependencies, as checked via mvn versions:display-dependency-updates -U and mvn versions:display-plugin-updates -U
• Require Maven 3.3.9 or newer
• Remove unused dependencies
• Change parser generator code from Maven Ant script to Java file
• Add generated parses to version control, remove timestamp comments
• Incorporate filevisitor code into candy-generator as an implementation detail