Merge pull request #34 from skybound/master

Added an optional build script flag to target the .NET Framework 4.5
Fix not saving global rules & GUI issues

Fix #35
Fix abstract methods not renamed

Fix #36
Two fixes for resolving paths on Unix-like systems:
1. Use Path.DirectorySeparatorChar instead of “\” when assigning BaseDirectory and OutputDirectory.
2. It’s possible that dnlib could provide the location of a module as a path relative to the current directory (in my observation).  Since Utils.GetRelativePath throws an exception when “filespec” is a relative path, the parameter must be made into an absolute path first.
The Confuser.Runtime project now uses the .NET 4.0 runtime when the NET45 compiler flag is used (like the other projects).  This ensures that processed assemblies reference only one version of mscorlib.
Don’t rename virtual methods which implement an interface method or override a method declared in a base type, when the interface or base type is declared in an assembly that is not currently being processed.