Fixed typos, bugs and merged more code from SPOnline.Core into Core

Fixed method typos in OfficeDevPnP.Core (created new correct methods names, marked the old once as obsolete and make them call the new correct ones). Merged more code from OfficeDevPnP.SPOnline.Core into OfficeDevPnP.Core, fixed a number of bugs in OfficeDevPnP.SPOnline.Commands