Change adapter package to use tools directory

[CharliePoole]

Use of the lib directory creates unneeded references in the user project. At times, they cause problems, particularly in the case of the Mono.Cecil reference. For example, the user may want to reference a different version of that assembly than we use. In addition, this reference may give rise to duplicate definitions of System.Runtime.CompilerServices.ExtensionAttribute.

When the adapter was originally developed, use of the lib directory was required. However, it appears that this has not been true since VS2012. Too bad this stuff isn't documented anywhere!