Check for EOF before every getline, and warn when reading gets to EOF
before the end of the data.
Stricter error checking could shed more light on issues such as #7463
and #7379.
- fixes #3136
- the problem is related to Boost path and a static initialized internal
pointer
- using a std::string in CDBEnv::EnvShutdown() prevents the problem
- this removes the boost::filesystem::path path field from CDBEnv
