Issue #1146: trim string before escaping

This removes leading and trailing whitespace before escaping strings. This gets rid of annoying `\n` in some string literals (e.g. in annotations).

modules/swagger-codegen/src/main/java/io/swagger/codegen/DefaultCodegen.java

@@ -126,6 +126,7 @@ public class DefaultCodegen {
     // override with any special text escaping logic
     public String escapeText(String input) {
         if (input != null) {
+            input = input.trim();
             String output = input.replaceAll("\n", "\\\\n");
             output = output.replace("\"", "\\\"");
             return output;