Provide is_similar_to() for all Machines in Bob

Created by: anjos

This issue was migrated from bug #104 (closed)

Provide is_similar_to(const Object& b, const double epsilon=1e-8) functions for all C++ classes that have double members. The default == and != operators are largely useless when we want to provide code that runs on several platforms (i.e., 32 and 64 bit machines).

Note (AA): Many classes already implement that. As soon as the remaining classes get fixed, this bug can be closed.