* http: add ErrUseLastResponse and Client.CloseIdleConnections
Both are API-compatibility fills. ErrUseLastResponse is a sentinel a
CheckRedirect func returns to stop following redirects; nothing here has
to act on it beyond existing. CloseIdleConnections delegates to the
Transport when it has the method, which is what net/http does.
Programs that reference either currently fail to compile against this
package for want of a name, which is the whole cost.
Moses Narrow
902c8d1203