Fix
Downgrade to .NET 4
CASCHandler - add ability to work with null BackgroundWorker
Extract LoadListFile method

Conflicts:
	CASCExplorer/CASCHandler.cs
Load listfile with a separate call

Conflicts:
	CASCExplorer/CASCHandler.cs
LoadListFile returns root folder
Add path argument to a LoadListFile
Make some classes and method public
KeyValueConfig refactoring
Encapsulate archives to CASCConfig
BLTEHandler refactoring
Update .gitignore
Reduce dependencies on Settings
Make CASCConfig non static
Move LoadListFile to MainForm
Create CascLib
Simplify opening of CASCHandler
Add methods to open and save files
Reduce methods and classes visibility
Split CASCHandler Open method