Style fix.
Core: Use typedefs for better readability.
Comment fix.
Added code for adding a new xml element.
Added new testcase for add and delete xml element.
style fix
Adjusted test for addAttribute.
Added remove Attribute function.
Adjusted testcase.
Added edit data function.
Added editAttributeData and a new addElement function.
adjusted testcase.
Merge branch 'master' of https://github.com/wITTus/Brute-Force-Game-Engine