Support reversible JsonML mapping by avoiding implicit type conversion

To introduce the opportunity to avoid implicit type conversion I have overloaded the parse method and added a new toJsonML(String) and a new toJsonML(XMLTokener) method using the overloaded parse method.
The changes have no impact on previously existing public methods - those should behave exactly as before.

One of the problems with the implicit type conversion is that xml data converted to json cannot be reverted to the original xml. Actually all non-string Json values are completely lost. This may be considered to be a separate problem of JSON.toString(JSONArray) which I did not try to solve directly, because for xml data converted using the new JsonML operations it is not relevant.

The following test case (groovy) illustrates the problems (testToJSONArray_*) and the solution (testToJsonML):

```groovy
import org.json.JSONML
import org.junit.Test

class JsonMLTestCase {
	def originalXml = '<root><id>01</id><id>1</id><id>00</id><id>0</id><item id="01"/><title>True</title></root>'
	def expectedJsonString = '["root",["id","01"],["id","1"],["id","00"],["id","0"],["item",{"id":"01"}],["title","True"]]'

	@Test // test fails - JSON string lost leading zero and converted "True" to true. See test result in comment below
	void testToJSONArray_jsonOutput() {
		def actualJsonOutput = JSONML.toJSONArray(originalXml)
		assert actualJsonOutput == expectedJsonString
	}
	
	@Test // test fails - JSON string cannot be reverted to original xml. See test result in comment below
	void testToJSONArray_reversibility() {
		def revertedXml = JSONML.toString(org.json.JSONML.toJSONArray(originalXml))
		assert revertedXml == originalXml
	}
	
	@Test // test passes when using the new method toJsonML
	void testToJsonML() {
		def json = JSONML.toJsonML(originalXml)
		def reverseXml = org.json.JSONML.toString(json)
		assert originalXml == reverseXml
		assert json.toString() == expectedJsonString
	}
}


/****************** Test result:
testToJSONArray_jsonOutput(JsonMLTestCase)
expexted: ["root",["id","01"],["id","1"],["id","00"],["id","0"],["item",{"id":"01"}],["title","True"]]
actual:   ["root",["id",1],["id",1],["id","00"],["id",0],["item",{"id":1}],["title",true]]

testToJSONArray_reversibility(JsonMLTestCase)
expexted: <root><id>01</id><id>1</id><id>00</id><id>0</id><item id="01"/><title>True</title></root>
actual:   <root><id></id><id></id><id>00</id><id></id><item id="1"/><title></title></root>
********************/
```