Improve performance of toString() methods #54

I've played a little bit with the code to improve the performance of toString() methods.

Here is a summary of most important changes:

• added write(Writer writer, int indentFactor, int indent) to both JSONObject and JSONArray, so now you can use indentation even with the write methods
• made toString() methods to use the write() method, but writing to a StringWriter. This also reduced the duplicate code!
• appending to a StringBuffer/StringWriter is synchronized to the StringBuffer. This makes append operations faster.

I've wrote a simple test to measure the performance between changes and here is the results:
D:\develop\json\douglascrockford-JSON-java-d98dc0b>java -cp org.apache.commons.io.jar;. PerfTest
str: 5206
D:\develop\json\douglascrockford-JSON-java-d98dc0b>java -cp org.apache.commons.io.jar;. PerfTest
str: 5241
D:\develop\json\douglascrockford-JSON-java-d98dc0b>java -cp org.apache.commons.io.jar;. PerfTest
str: 5280
D:\develop\json\douglascrockford-JSON-java-d98dc0b>cd ..\new-json
D:\develop\json\new-json>java -cp org.apache.commons.io.jar;. PerfTest
str: 2912
D:\develop\json\new-json>java -cp org.apache.commons.io.jar;. PerfTest
str: 2946
D:\develop\json\new-json>java -cp org.apache.commons.io.jar;. PerfTest
str: 2912

This means that the average milliseconds for the old code is 5242 and 2923 for the new code. This means that the new code is ~1.8 times faster that the original code.

Here is a zip file (http://depositfiles.com/files/vnfv5budt) that includes:

• updated JSONObject and JSONArray code
• PerfTest.java
• screenshot of the output from PerfTest.java

I cannot include the JSON file I've been testing with, but it contains various data types, JSON objects and arrays. It is at about 74K big.