Added an XMLTool in the main vooga util folder

The XMLTool was created to facilitate the creation and parsing of an
XML file. The code is still not complete and can accept many more
features and refactoring. The code has passed CheckStyle, but there are
further improvements pending with the code efficiency and comment
quality. The main functions were added to the XMLToolExample.java file.
Fixed package references.
Deleted old XMLTool.
Added a new getter method for convenience

After working with some factories, I found useful to have a way to get
a map from just a tag string.
Edited a method name.

Minor Commit. (Hope no one used this method yet...)
Refactored the XMLTool.

Changed the constructor to automatically read an XML file.
Overloaded some methods.
Tried to solve some auto merging issues.
Merging master to this branch.
Merging again...
Deleted all code.
Added everything back. Brutal solution for the merge conflicts.
Merge branch 'master' into XMLTool
Added back the XMLTool and the simple example.
Created a way to get a map of children elements from a specific parent.
Added more functionality to the XMLTool. Refactored some code. Merged master to this branch.
Updated the XML Example.
Added proper identation to the generated XML file.
Refactored some code.
Minor changes in comments and corrected typo.
Added default exception message variables.