CHANGED: major refactor if ModPackPanes

 * Moved similar code from FTBPacksPane and ThirdPartyPane into
   new AbstractModPackPane.java
 * Converted private/static variables and functions mostly publics
 * Renamed function
 * Fixed other classes to call member function instead of calling static
   funtions
Merge pull request #751 from jikuja/fixed_modpacktabs_and_textures

CHANGED: major refactor if ModPackPanes