Escape some characters in xunit_results.xml

[pascalwolterink]

Hi,

First of all we love your work! We are using your framework for some time now and found a problem with the xml results.

Assert Messages and TestNames are not properly escaped in the xunit_testresults.xml

If you would add a " character in either the Assert Message or TestName the xunit_testresults.xml cannot be properly parsed by xml parsers. To fix this problem I've implemented a F_XmlEscapeString function. For now I followed the 'safe' approach as suggested in this link https://stackoverflow.com/a/1091953.

Sample test code that will create the problem in the xml file:

TEST('Test_EscapedFailedMessage');
AssertTrue(FALSE, 'This "string" <should> be $'escaped$' & parsed properly');
TEST_FINISHED();

TEST('Test_EscapedFunctionName$'"<>&');
TEST_FINISHED();

These tests result in:

<?xml version="1.0" encoding="UTF-8"?>
<testsuites disabled="" failures="1" tests="2" time="8.38e-5">
	<testsuite id="26" name="PRG_TEST.TestXUnitPublisher" tests="2" failures="1" time="7.47e-5">
		<testcase name="Test_EscapedFailedMessage" classname="PRG_TEST.TestXUnitPublisher" time="6.15e-5" status="FAIL">
			<failure message="This " string"
			<should> be 'escaped' & parsed properly" type="BOOL"/></testcase>
			<testcase name="Test_EscapedFunctionName'"
			<>&" classname="PRG_TEST.TestXUnitPublisher" time="1.0e-7" status="PASS"></testcase>
		</testsuite>
	</testsuites>

But should be:

<?xml version="1.0" encoding="UTF-8"?>
<testsuites disabled="" failures="1" tests="2" time="3.602e-4">
	<testsuite id="26" name="PRG_TEST.TestXUnitPublisher" tests="2" failures="1" time="3.602e-4">
		<testcase name="Test_EscapedFailedMessage" classname="PRG_TEST.TestXUnitPublisher" time="3.351e-4" status="FAIL">
			<failure message="This &quot;string&quot; &lt;should&gt; be &apos;escaped&apos; &amp; parsed properly" type="BOOL"/>
		</testcase>
		<testcase name="Test_EscapedFunctionName&apos;&quot;&lt;&gt;&amp;" classname="PRG_TEST.TestXUnitPublisher" time="1.0e-7" status="PASS"/>
	</testsuite>
</testsuites>

I've tried to add some basic tests, but I'm not happy with the requirement that is now should be run on a local machine for this to work. I'm happy to omit these tests or adjust this if needed.

Please let me know what you think of this change.

(Note: this is the first time I'm actively contributing to a project, so please let me know if I should do anything different next time :) )