This allows users to set a client name to use. The idea is that this lets users set the client to use for a certain directory tree, when they have multiple clients they use.
** CHANGED Enabled ~lexical-binding~
Both =vc-p4.el= and =p4-lowlevel.el= now use lexical binding instead of dynamic binding.
** ADDED ~vc-p4-login~ command
This interactive command lets you log in to Perforce when your session has expired.