Add a testing framework

Hi,

I am Tina. I am quite interested on the idea: Add a testing framework

I found that there was no much test on ABiword. Firstly, I would like
to use CppUnit  to cover some Unit test case on platform free code.

Unit test is important to a open source code. Unit Tests have several
benefits to us. It allows us changing code quickly under full testing.
By running unit tests, a developer can identify whether his latest
changes to the code base has broken anything. Unit Tests can also help
new developers really understand the design of the code and it can
give our developers visual feedback about which lines are covered.

At least three things should be done:
1. add some unit test case
2  add script to automatically run it
3  help other developers to add their own unit test case


Any opinion?

Tina