Merge branch 'error_filenames' into 'master'

src/main/jastadd/Errors.jrag

src/main/jastadd/RelAst.ast

src/main/jastadd/RelAst.parser

src/main/java/org/jastadd/relast/compiler/Compiler.java

src/test/jastadd/errors/Errors.expected

src/test/jastadd/errors/Inheritance.expected

src/test/jastadd/errors/Multiple.expected

src/test/jastadd/errors/Multiple_1.relast

src/test/jastadd/errors/Multiple_2.relast

src/test/java/org/jastadd/relast/tests/Errors.java