Always refresh grammars with changed dependencies

The buildContext.hasDelta function is ignorant of importants. Since we have more advanced
dependency analysis, stop relying on hasDelta and instead just refresh grammars where we
know the dependencies have changed.

antlr4-maven-plugin/src/main/java/org/antlr/mojo/antlr4/Antlr4Mojo.java

@@ -412,10 +412,7 @@ public class Antlr4Mojo extends AbstractMojo {
 		// Iterate each grammar file we were given and add it into the tool's list of
 		// grammars to process.
 		for (File grammarFile : grammarFiles) {
-			if (!buildContext.hasDelta(grammarFile)) {
-				continue;
-			}
-
+			buildContext.refresh(grammarFile);
 			buildContext.removeMessages(grammarFile);
 
 			getLog().debug("Grammar file '" + grammarFile.getPath() + "' detected.");