Allow carriage return and tabs. fix #699

Author: jknack

handlebars/src/main/antlr4/com/github/jknack/handlebars/internal/HbsLexer.g4

@@ -337,7 +337,7 @@ ID
 fragment
 ID_START
   :
-   [a-zA-ZА-Яа-я_$@:\u0001-\u0009\u000b\u000c\u000e-\u001E\u00C0-\u00FF]
+   [a-zA-ZА-Яа-я_$@:\u0001-\u0008\u000b\u000c\u000e-\u001E\u00C0-\u00FF]
   ;
 
 fragment

handlebars/src/test/java/com/github/jknack/handlebars/internal/HbsParserTest.java

@@ -6,6 +6,8 @@
 import org.antlr.v4.runtime.tree.ParseTree;
 import org.junit.Test;
 
+import static org.junit.Assert.assertEquals;
+
 public class HbsParserTest {
 
   private boolean printTokens = true;
@@ -118,6 +120,21 @@ public void setDelim() {
     parse("{{=+-+ +-+=}}+-+test+-+");
   }
 
+  @Test
+  public void whiteSpaceHandledEqually() {
+    String withSpace = "{{helper param1=\"1\" param2=2}}";
+    ParseTree tree = parse(withSpace);
+
+    String withNewlines = "{{helper\nparam1=\"1\"\nparam2=2}}";
+    assertEquals("Newlines should be treated the same as spaces", tree.getText(), parse(withNewlines).getText());
+
+    String withDosNewlines = "{{helper\r\nparam1=\"1\"\r\nparam2=2}}";
+    assertEquals("DOS-style newlines should be treated the same as spaces", tree.getText(), parse(withDosNewlines).getText());
+
+    String alignedWithTabs = "{{helper\n\tparam1=\"1\"\n\tparam2=2}}";
+    assertEquals("Tab-aligned variables should be treated the same as spaces", tree.getText(), parse(alignedWithTabs).getText());
+  }
+
   private ParseTree parse(final String input) {
     return parse(input, "{{", "}}");
   }