Turn global variable usage order warning into error

Author: Frotty

de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/validation/ValidateGlobalsUsage.java

@@ -61,8 +61,7 @@ public void visit(ExprVarAccess e) {
                     if (!definedVars.contains(g)
                             && !g.attrIsDynamicClassMember()
                             && g.attrNearestNamedScope() == p) {
-                        e.addWarning("Global variable " + e.getVarName() + " must be declared before it is used. " +
-                                "This will be an error in future Wurst versions.");
+                        e.addError("Global variable <" + e.getVarName() + "> must be declared before it is used.");
                         // add variable to defined vars to silence further warnings:
                         definedVars.add(g);
                     }

de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/BugTests.java

@@ -132,7 +132,7 @@ public void test_init_order_jass_warning() {
 
     @Test
     public void test_init_order_globals_warning() {
-        testAssertErrorsLines(false, "Global variable b must be declared before it is used.",
+        testAssertErrorsLines(false, "Global variable <b> must be declared before it is used.",
                 "package test",
                 "	integer a = b",
                 "	integer b = 3",